REESE   LIBRARY 

OF  THK 

UNIVERSITY  OF  CALIFORNIA. 


e/lccessions 


f      Class  No. 


ANALYSIS  OF  MILK  AND  MILK  PRODUCTS 


LKFFMANN  AND  BEAM. 


EXAMINATION    OF    WATER 

FOR    SANITARY  AND    TECHNICAL  PURPOSES 

BY 

HENRY  LEFFMANN  AND  WIW,IAM  BEAM. 
Second  Edition.     I2mo.     130  pages.     Illustrated.     $1.25. 


A   COMPEND   OF    CHEMISTRY 

INORGANIC    AND    ORGANIC    INCLUDING  URINARY  ANALYSIS 

BY 

HENRY  LEFFMANN. 

Especially  adapted  to  Students  in  Medicine  and  Dentistry. 

Third  Edition.     Revised,     Price  $1.00.     Interleaved  for  taking 

Notes,  $1.25. 


SANITARY  RELATIONS 

OF  THE 

COAL     TAR     COLORS 
BY  THEODORE  WEYI,, 

Authorized  Translation  by  HENRY  L/EFFMANN. 
I2mo.     154  pages.     $1.25. 


P.   BLAKISTON,  SON  &  CO. 


ANALYSIS 


OF 


MILK  AND  MILK  PRODUCTS 


BY 


HENRY  LEFFMANN,  M.  D.,  PH.  D., 

« tf 

PROFESSOR  OF  CHEMISTRY  IN  THE  WOMAN'S  MEDICAL  COLLEGE  OF  PENNSYLVANIA, 

IN  THE  PENNSYLVANIA  COLLEGE   OF  DENTAL  SURGERY  AND    IN  THE 

WAGNER  FREE  INSTITUTE  OF  SCIENCE;    PATHOLOGICAL 

CHEMIST   TO    THE   JEFFERSON    MEDICAL 

COLLEGE     HOSPITAL, 


WILLIAM  BEAM,  M.  A.,  M.  D., 

FORMERLY  CHIEF  CHEMIST  B.   &  O.  R.  R. 


PHILADELPHIA : 

P.    BLAKISTON,    SON  &    CO., 

1012     WAL,NUT     STREET. 
I893. 


I 

v\ 
V\ 


Copyright  1893,  by  P.  BLAKISTON,  SON  &  Co. 


PR»NTED  BY  E.   F.  GREATHEAD 
909    SANSOM    STREET 
PHILADELPHIA 


PREFACE. 

The  analysis  of  dairy  products  has  been  the  subject 
of  so  much  exact  investigation  within  the  last  few 
years,  that  most  of  the  earlier  processes  have  been 
abandoned,  since  it  has  been  shown  that  the  data  de- 
rived from  them  are  inaccurate.  In  the  present  work 
we  have  had  in  view  the  object  of  providing  not  only 
methods  suitable  for  professional  chemists,  but  also 
such  as  may  be  safely  employed  by  dairymen  and 
others  unskilled  in  general  analytical  work.  To  aid  in 
securing  uniformity,  we  have  described  some  of  the 
published  methods  of  the  Association  of  Official 
Agricultural  Chemists,  selecting  those  that  we  find  to 
be  satisfactory. 

We  have  drawn  freely  from  the  valuable  material 
contributed  to  The  Analyst  and  these  references  will 
show  how  large  a  part  of  the  advance  in  the  analytical 
practice  in  this  field  is,  due  to  the  industry  and  inge- 
nuity of  the  members  of  the  Society  of  Public  Anal- 
ysts. We  have  constructed  a  table,  based  on  the  form- 
ula of  Hehner  and  Richmond,  arranged  to  suit  the 
method  of  calculating  total  solids  from  the  fat  and 
specific  gravity.  Several  other  tables,  not  easily  ac- 
cessible, have  been  added,  the  insertion  of  which  will 
contribute  to  the  usefulness  of  the  work. 

Walnut  St.,  Phila.  H.  L. 

July,  189$.  W.  B. 


CONTENTS. 

NATURE  AND  COMPOSITION  OF  MILK. 

Formation  and  Ingredients  of  Cow's  Milk. — Colos- 
trum— Milk  of  Various  Animals — Properties  and 
Decompositions  of  Milk — Skimmed  Milk — Butter- 
milk,    10-14 

ANALYTICAL  PROCESSES. 

Specific  Gravity — Total  Solids — Ash — Fat — Pro- 
teids— Sugar— Milk  Adulterants,  .  .  .  15-46 

DATA  FOR  MILK  INSPECTION. 

Variations  in  Composition — Sanitary  Relations,      47-59 

MILK  PRODUCTS. 

Condensed  Milk — Butter — Cheese,  .         .         60-78 

APPENDIX. 

Table  for  Correcting  Specific  Gravity — 

Table  for  Calculating  Total  Solids,  79-§9 


NATURE  AND  COMPOSITION  OF  MILK 


Milk,  by  which  term  is  to  be  understood  the  nutri- 
tive secretion  of  nursing  mammalia,  consists  of  water 
holding  fat  in  suspension,  and  nitrogenous,  saccharine 


ERRATA 

Page  10,  line  3,  for  ".035  to  .050"  read  "0.35  to  0.50." 
Page  65,  line  10,  insert  a  quotation  mark  after  word  "aah.] 


eration  of  the  epithelial  cells  lining  the  ducts  of  the 
mammary  gland.  It  occurs  in  the  form  of  minute 
globules  from  .0015  mm.  to  .005  mm.  in  diameter, 
under  conditions  which  prevent  spontaneous  coales- 
cence. Films  of  proteid  matter  are  also  abundant. 
A  form  of  sugar,  isomeric  with  cane-sugar,  and  called 
lactose,  is  present. 

B  9 


NATURE  AND  COMPOSITION  OF  MILK 


Milk,  by  which  term  is  to  be  understood  the  nutri- 
tive secretion  of  nursing  mammalia,  consists  of  water 
holding  fat  in  suspension,  and  nitrogenous,  saccharine 
and  mineral  matters  in  solution.  Cow's  milk,  being 
of  the  greatest  importance  to  the  analyst,  will  receive 
the  largest  share  of  attention,  and  will  be  under- 
stood to  be  meant  in  all  cases,  unless  otherwise 
stated. 

With  rare  exceptions,  the  secretion  of  milk  takes 
place  only  as  a  result  of  pregnancy  and  delivery  at 
term,  and  continues  for  a  variable  period.  The  chem- 
istry of  its  formation  is  not  entirely  understood.  The 
organic  ingredients  do  not  exist  in  appreciable  quanti- 
ties in  the  blood,  and  must,  therefore,  be  elaborated  by 
specific  secretory  action.  The  fat  has  been  regarded 
by  many  authorities  as  resulting  from  the  fatty  degen- 
eration of  the  epithelial  cells  lining  the  ducts  of  the 
mammary  gland.  It  occurs  in  the  form  of  minute 
globules  from  .0015  mm.  to  .005  mm.  in  diameter, 
under  conditions  which  prevent  spontaneous  coales- 
cence. Films  of  proteid  matter  are  also  abundant. 
A  form  of  sugar,  isomeric  with  cane-sugar,  and  called 
lactose,  is  present. 

B  9 


10  NATURE  AND  COMPOSITION  OF  MILK. 

The  proteids  of  milk  consist  largely  of  casein. 
There  is  also  some  albumin  (the  form  called  lactal- 
bumin)  from  .0^35  to  .0^50  per  cent,  being  usually 
present,  together  with  traces  of  globulin.  The  albumin 
is  coagulated  by  boiling.  The  condition  in  which  the 
casein  exists  is  still  obscure,  but  the  results  of  recent 
investigation  render  it  probable  that  it  is  in  combina- 
tion with  the  calcium  phosphate.  Acids  break  up  this 
combination,  and  precipitate  the  casein  in  an  insoluble 
form.  Heat  alone  does  not  produce  this  effect.  The 
form  in  which  the  casein  exists  prior  to  coagulation  is 
now  frequently  called  "  caseinogen  ".. 

Citric  acid  is  a  normal  constituent  of  the  milk  of 
various  animals.  In  human  milk,  the  quantity  is  about 
0.5  gram  to  the  liter,  in  cow's  milk  from  I  to  1.5 
grams.  It  is  not  dependent  on  the  citric  acid  present 
in  the  food. 

Minute  amounts  of  nitrogenous  bases  and  a  starch 
converting  enzyme  also  occur. 

The  ash  of  milk  has   the   following   composition  : 

Ca  .  .113      percent,     (of  milk) 

Mg  .  .  .0126          "                 " 

Fe  .  .  .0002          "                 " 

K  .  .  .146 

Na  .  .  .082 

P04  f.  .  .263 

SO4  .  .  traces 

Cl  .  .  .169 

CO*  .020 


COLOSTRUM. 


11 


Colostrum. — The  milk  secreted  in  the  early  stage 
of  lactation  is  rich  in  proteids  (20  per  cent,   or  more) 
due  probably  to  the  incomplete  transformation  of  the 
epithelial  lining  of  the  ducts.     A  protoplasmic  struct- 
ure  known  as  the  colostrum  corpuscle  is  found  at  this 
period.     The  large  proportion  of  proteids  is  often  suffi- 
cient to  cause  the  liquid  to  coagulate  on  boiling.     The 
following  is  an  average  composition  of  colostrum  : 
Fat  ......  3.5 

Proteids  .         .         .         .         .         .          12.7 

Sugar 4.2 

Ash  0.8 


21.2 


The  following  table  is  a  compilation   of  published 
statements  of  the  composition  of  various  milks. 


Specific 
Gravity 

3 
| 

5           o     •      ? 
W           O            ^ 

2 

I           *'                  « 
a           SSI 

<  ;  w 

i 

about 
•     •        •    •    looo.o 

1034.  9 

1035.4  1032.9 

Fat    ...         3-5     3-9    45.8o 

1.09 

5.56        4.3     1.6    6.8    4-8 

Sugar    .    .         6.5     4.7-     1.33 

6.65 

5.41        4.0     6.1    4.8    3.4 

Proteids  .  .         1.6     3.7     11.19 

1.89 

3.86        4.6    2.2    6.3    1.3 

Ash    .    .    . 
Tot'lSoiids 

Analyst 

0.25     0.7.     0.57 

0.31 

1.03        0.6    0.5    0.8    0.9 

11.80  13.0    58.89 

9.94 

15.86       13.5  10.4  18.7  15-4 

• 

I 

| 

H 

12  NATURE    AND    COMPOSITION  OF  MILK. 

Normal  milk  is  an  opaque,  white  or  yellowish- 
white  fluid,  with  an  odor  recalling  that  of  the  animal, 
and  a  faint  sweet  taste.  The  opacity  is  due  partly  to 
the  fat  globules,  but  when  these  are  entirely  removed 
the  liquid  does  not  become  transparent.  The  reaction 
of  freshly  drawn  milk  is  amphoteric,  that  is,  it  turns  red 
litmus  paper  blue  and  blue  litmus  paper  red.  The 
specific  gravity  varies  between  1028  and  1035.  It 
undergoes  a  gradual  augmentation  for  a  considerable 
time  after  the  sample  has  been  drawn.  The  increase  may 
amount  to  two  units.  The  specific  gravity  becomes 
stationary  in  about  five  hours,  if  the  milk  be  maintained 
at  a  temperature  below  60°  F.,  but  at  a  higher  temper- 
ature it  may  require  twenty-four  hours  to  acquire  con- 
stancy. The  change  is  not  dependent  on  the  escape 
of  gases,  and  is  believed  to  be  due  to  some  molecular 
modification  of  the  casein. 

Unless  collected  with  special  care  and  under  condi- 
tions of  extreme  cleanliness,  milk  always  contains  bac- 
teria and  animal  matter  of  an  offensive  character, 
such  as  epithelium,  blood  and  pus  cells,  particles  of 
feces  and  soil.  Many  minute  organisms,  especially 
bacteria,  propagate  with  great  rapidity  in  milk  and 
produce  changes  in  its  composition.  Some  specific 
organisms,  such  as  the  Spirillum  cholera,  multiply  to 
only  a  limited  extent  in  ordinary  milk,  being  hamper- 
ed by  the  bacteria  normally  present,  but  when  intro- 
duced into  sterilized  milk  increase  with  great  rapidity. 

At  ordinary  temperature  milk  soon  undergoes  de- 
composition under  the  influence  of  the  microorgan- 


DECOMPOSITION    OF    MILK.  13 

isms  present,  by  which  the  milk  sugar  is  converted 
principally  into  lactic  acid,  and  the  proteids  partly  de- 
composed and  partly  coagulated.  The  liquid  becomes 
sour  and  the  fat  is  enclosed  in  the  coagulated  casein. 

In  the  initial  stages  of  decomposition  the  proteids 
frequently  undergo  transformations  into  highly  poison- 
ous benzene  derivatives,  among  which  diazobenzene, 
commonly  known  as  tyrotoxicon,  is  the  most  important. 
This  body  is  the  cause  of  the  violent  poisonous  effects 
occasionally  produced  by  ice  cream  and  other  articles 
of  food  into  the  preparation  of  which  milk  enters. 

Boiling  produces  coagulation  of  the  albumin,  some 
alteration  of  the  sugar,  and  developes  a  greater  fac- 
ility of  coalescence  on  the  part  of  the  fat  globules. 
Microbes  and  enzymes  are  destroyed.  The  scum 
which  appears  on  the  surface  of  boiling  milk  is  com- 
posed largely  of  casein.  Its  formation  is  due  probably  to 
the  more  rapid  evaporation  at  the  surface  of  the  liquid. 

Precipitation  of  the  casein  in  the  form  of  a  curd,  en- 
closing the  fat,  occurs  promptly  on  the  addition  of 
rennet  or  free  acids. 

Partial  freezing  produces  a  concentration  of  the  milk 
solids  in  the  part  remaining  liquid,  while  the  solid  por- 
tion is  deficient  in  them.  The  normal  condition  can, 
therefore,  be  restored  only  by  thawing  the  entire  mass, 
and  mixing  thoroughly. 

When  milk  is  allowed  to  stand,  some  of  the  fat  rises 
gradually,  and  forms  a  rich  layer,  constituting  cream. 
The  proportion  of  cream  depends  on  several  condi- 
tions. The  amount  formed  in  a  given  time  cannot  be 


14  NATURE  AND    COMPOSITION    OF    MILK. 

taken  as  a  measure  of  the  richness  of  the  milk.  Water 
added  to  milk  causes  a  more  rapid  separation  of  the 
cream.  When  milk  is  subjected  to  centrifugal  action, 
a  much  larger  proportion  of  cream  is  obtained,  prac- 
tically all  of  the  fat  being  removed.  The  following 
figures  given  by  D'Hout  as  averages,  show  the  effect 
of  the  centrifugal  action : 

Whole  milk      Skimmed  milk       Cream 

Specific  gravity  1032  JO34  1015 

Total  solids  14.10  9.6  26.98 

Sugar  4.70  5.05  3.32 

Casein  3.50  3.62  2.02 

Ash  0.79  0.78  0.58 

Fat  5.05  0.02  21.95 

Buttermilk  is  the  residue  after  removal  of  the  but- 
ter by  churning.     Vieth  gives  the  following  figures  : 
Total  solids  Fat  Solids  not  fat  Ash 

9.03  0.63  8.40  0.7O 

8.02  0.65  7.37  1.29 

10.70  0.54  10.16  0.82 


ANALYTICAL  PROCESSES. 

SPECIFIC   GRAVITY. 

%  /.•< 

Determinations  of  specific  gravity  of  milk  are  un- 
derstood to  be  taken  at  the  temperature  of  6o°F.,  and 
samples  at  temperatures  different  from  this  should  be 
brought  to  it.  If  at  a  few  degrees  above  or  below 
60°  it  will  suffice  to  take  the  gravity  at  once,  and  obtain 
the  correct  figures  by  reference  to  Table  A. 

The  specific  gravity  of  normal  milk  varies  be- 
tween 1028  and  1035,  being  less  in  porportion 
as  the  fat  is  greater.  A  milk,  the  specific  gravity 
of  which  has  been  raised  by  the  abstraction  of 
fat  (skimming)  can  be  restored  to  the  original  specific 
gravity  by  the  addition  of  water,  so  that  this  figure 
taken  alone  cannot  be  relied  upon  as  an  index  of  the 
character  of  the  sample.  Taken  in  conjunction  with 
the  figure  for  fat  or  for  total  solids,  it  is  of  the 
greatest  value,  and  should  be  ascertained  as  a  check  on 
the  results  furnished  by  other  determinations. 

Air  bubbles  are  held  rather  tenaciously  by  milk  and 
care  must,therefore,  be  taken  in  mixing  the  samples  pre- 
paratory to  taking  the  density,  to  avoid  as  far  as  possible 
the  enclosure  of  air,  and  to  allow  sufficient  time  for  the 
escape  of  any  bubbles  that  may  be  present. 

15 


16  ANALYTICAL    PROCESSES. 

The  simplest  method  of  determining  specific  grav- 
ity is  by  the  lactodensimeter,  a  delicate  and  accurately 
graduated  hydrometer.  The  instrument  must  be  im- 
mersed carefully  so  as  not  to  wet  the  stem  above  the 
point  at  which  it  will  rest.  The  reading  should  be 
made  at  the  actual  level  of  the  liquid,  and  not  at  the 
point  to  which  it  is  drawn  by  adhesion  to  the  glass. 

The  indications  furnished  by  the  lactodensimeter  are 
sufficiently  accurate  for  most  purposes,  but  its  employ- 
ment necessitates  a  considerable  amount  of  the  sample. 
More  accurate    determination  can  be  made  by  the 

Westphal  balance.  This  is 
a  delicate  steelyard  with  a 
counterpoised  plummet,  dis- 
placing 5  c.  c.  The  plum- 
met being  immersed  in  the 
milk  the  equilibrium  is  re- 
stored by  weights,  the  value 
of  which  can  be  directly  ex- 
pressed in  figures  for  the 
specific  gravity. 
The  principal  of  the  Westphal  balance  may  be  ap- 
plied by  means  of  the  ordinary  analytical  balance  and 
a  plummet.  The  latter  may  conveniently  consist  of  a 
short  thermometer,  or  a  thick  glass  rod,  having  a  bulk 
of  from  5  to  10  c.  c.  It  is  suspended  from  the  hook  of 
the  balance  by  a  fine  platinum  wire  and  its  weight  as- 
certained. It  is  then  immersed  in  distilled  water  at 
60° F.  and  the  loss  in  weight  noted.  The  figure  so  ob- 
tained is  the  weight  of  a  bulk  of  water  equal  to  that  of 


SPECIFIC    GRAVITY.  1J 

the  plummet.  This  having  been  determined,  the  spe- 
cific gravityof  a  milk  may  be  found  by  immersing  the 
plummet  in  it,  and  noting  the  loss  in  weight,  which, 
divided  by  the  loss  in  pure  water,  gives  the  specific 
gravity. 

The  pyknometer  or  specific  gravity  bottle  furnishes  a 
means  of  accurately  determining  specific  gravity  and  is 
especially  suitable  when  only  a  small  amount  of  liquid 
is  available.  It  consists  of  a  small  flask  provided  with  a 
finely  perforated  glass  stopper.  The  flask  is  weighed, 
first  alone,  then  filled  with  waterat  6o°F.,  then  with  the 
milk  at  the  same  temperture.  In  filling  the  flask  the 
liquid  is  first  brought  to  the  proper  temperature,  the 
bottle  completely  filled,  the  stopper  inserted  and  the 
excess,  forced  out  through  the  perforation  and  around 
the  sides  of  the  stopper,  removed  by  bibulous  paper. 
The  weight  of  milk  divided  by  that  of  an  equal  bulk 
of  water  gives  the  specific  gravity. 


TOTAL  SOLIDS. 

These  are  determined  by  evaporation  in  a  shallow, 
flat-bottomed  platinum  or  porcelain  dish  from  7  to  8  cm. 
in  diameter.  The  milk  must  be  spread  evenly  in  a  thin 
layer.  If  the  ash  is  also  to  be  determined,  about  five 
grams  should  be  accurately  weighed  in  the  dish,  evap- 
orated rapidly  to  apparent  dryness  over  the  water-bath 
and  the  heating  continued  in  the  water-oven  until  the 
weight  becomes  practically  constant,  which  will  require 


18  ANALYTICAL    PROCESSES. 

about  three  hours.  When  the  ash  is  not  to  be  deter- 
mined, it  is  more  convenient  to  follow  the  method  sug- 
gested by  Richmond,  using  I  to  2  grams,  accurately 
weighed.  The  drying  can  be  completed  in  about  one 
and  a  half  hours. 

Richmond  has  pointed  out  that  if  the  evaporation 
be  slow,  some  decomposition  occurs,  and  the  residue 
will  be  brown,  but  that  if  the  larger  portion  of  the 
water  be  evaporated  quickly,  a  white  residue  is  ob- 
tained. He  suggests  the  following  method  for  use 
when  a  higher  degree  of  accuracy  is  desired : 

About  3  grams  of  abestos  of  the  best  quality  are 
placed  in  a  platinum  dish,  ignited  in  a  muffle  and 
weighed.  By  simple  ignition  over  the  Bunsen  burner 
the  combined  water  is  not  always  lost.  5  grams  of 
milk  are  added  and  dried  on  the  water-bath  for  about 
two  hours.  The  residue  is  then  left  in  the  air  or  water- 
oven  at  about  208° F.  for  twelve  hours  or  more  (usually 
over  night).  At  the  end  of  this  time  an  absolutely 
constant  weight  is  obtained. 

The  residue  serves  well  for  the  determination  of  the 
ash. 

Where  rigid  accuracy  is  not  essential,  it  will  suffice 
to  measure  the  portion  of  milk  taken  for  this  and  other 
determinations.  Vieth  uses  a  pipette  graduated  to  de- 
liver 5  grams  and  finds  that,  working  with  whole  and 
skimmed  milk,  under  the  ordinary  variations  of  temper- 
ture,  the  error  will  not  exceed  O.I  on  the  total  solids 
and  is  less  on  the  fat. 


TOTAL   SOLIDS.  1£ 

A  better  plan  is  to  use  a  5  c.  c.  pipette  and  to  wash 
out  that  which  adheres  to  the  glass  with  a  little  water. 
The  specific  gravity  of  the  milk  being  known,  the 
amount  taken  can  be  calculated.  The  milk  should  be 
as  near  60°  F.  as  possible. 

ASH. 

The  residue  from  the  determination  of  total  solids  is 
heated  cautiously  over  the  Bunsen  burner,  until  a  white 
ash  is  left.  The  result  obtained  in  this  manner  is  apt 
to  be  slightly  low  from  loss  of  sodium  chloride.  This 
may  be  avoided  by  heating  the  residue  sufficiently  to 
char  it,  extracting  the  soluble  matter  with  a  few  c.  c. 
of  water,  and  filtering  (using  paper  extracted  with  hy- 
drofluoric acid.)  The  filter  is  added  to  the  residue,  the 
whole  ashed,  the  filtrate  then  added  and  the  liquid 
evaporated  carefully  to  dryness.  The  ash  of  normal 
milk  is  about  0.7  per  cent,  and  faintly  alkaline;  if  the 
milk  be  watered  the  ash  will  be  less.  It  will  be  seen 
by  the  detailed  statement  of  composition  that  it  is  prac- 
tically free  from  sulfates,  and  hence  a  quantitive  deter- 
mination of  these  may  detect  the  adulteration  with 
water  containing  sulfates.  For  this  purpose,  not  less 
than  100  c.  c.  should  be  taken.  A  marked  degree  of 
alkalinity  and  effervescence  with  hydrochloric  acid,  will 
suggest  the  addition  of  a  carbonate. 

FAT. 

The  method  introduced  by  Wanklyn  for  the  deter- 
mination of  fat  by  extracting  it  with  ether  from  the 


20  ANALYTICAL    PROCESSES. 

total  solid  residue,  has  been  found  to  give  results  0.5 
per  cent  or  more  below  the  correct  figure,  and  is  there- 
fore not  described. 

Adams'  Method. — This  consists  essentially  in 
spreading  the  milk  over  absorbent  paper,  drying,  and 
extracting  the  fat.  By  this  means  the  milk  is  dis- 
tributed in  an  extremely  thin  layer,  and  by  a  selective 
action  of  the  paper,  the  larger  portion  of  the  fat  is  left 
on  the  surface.  The  extraction  is  performed  by  means 
of  ether,  in  a  Soxhlet  apparatus.  It  is  essential  that 
the  paper  be  free  from  matters  soluble  in  ether.  A  fat- 
free  paper,  manufactured  by  Schleicher&  Schuell,  is 
obtainable  in  strips  suitable  for  the  purpose.  Each 
of  these  yields  to  ether  from  .001  to  .002  gram  of 
extract,  and  as  this  would  only  increase  the  figure  for 
fat  by  .003  per  cent.,  the  error  may  be  disregarded. 
•  The  procedure  is  as  follows :  5  c.  c.  of  the  milk  are 
discharged  into  a  beaker  5  cm.  high  and  3.5  cm.  in  di- 
ameter. The  charged  beaker  is  weighed,  and  a  strip  of 
the  paper  which  has  been  rolled  into  a  coil,  thrust  into 
it.  In  a  few  minutes,  the  paper  will  absorb  nearly  the 
whole  of  the  milk.  The  coil  is  then  carefully  withdrawn, 
and  stood  dry  end  downward  on  a  sheet  of  glass. 

With  a  little  dexterity,  all  but  the  last  fraction  of  a 
drop  will  be  absorbed  by  the  paper.  The  beaker  is 
again  weighed  and  the  milk  taken  found  by  difference. 
It  is  of  importance  to  take  up  the  whole  of  the  milk 
from  the  beaker,  as  the  paper  has  a  selective  action, 
removing  the  watery  constituents  by  preference  over 


ADAMS     METHOD. 


21 


the  fat.  The  charged  paper  is  placed  in  the 
water-oven  on  a  glass  plate,  milk  end  up- 
wards, and  dried.  In  about  an  hour  it  is 
usually  in  a  suitable  condition  for  the  ex- 
traction of  the  fat.  It  is  inserted  in  a  Soxh- 
let  continuous  extraction  apparatus,  the 
tared  flask  of  which  should  have  a  capacity 
of  about  150  c.c.  and  contain  about  75  c.c. 
of  ether.  Heat  is  applied  to  the  flask  by 
means  of  a  water  bath,  or  by  resting  it  on 
a  piece  of  asbestos  paper,  which  is  heated 
by  a  small  flame.  After  the  coil  has  re- 
ceived ten  or  twelve  washings,  the  flask  is 
detached,  the  ether  removed  by  distillation 
and  the  fat  dried  by  heating  in  an  air  oven, 
at  about  22O°F  ,  and  occasionally  blowing 
air  through  the  flask.  After  cooling,  the- 
flask  is  wiped  with  a  piece  of  silk,  allowed 


to  stand  ten  minutes  and  weighed. 


A  convenient  method  of  spreading  the  milk  over 
the  paper  and  arranging  the  coil  is  described  by  Allen. 
The  strip  is  rolled  up,  together  with  a  piece  of  thin 


ANALYTICAL     PROCESSES. 


string  (previously  boiled  with 
water  containing  sodium  car- 
bonate to  remove  size  and  res- 
inous matters)  which  serves  to 
prevent  contact  between  the  con- 
centric folds  of  the  coil,  and  is 
conveniently  passed  through 
holes  in  the  paper.  A  cap  of 
filter  paper  is  then  placed  over 
one  end  of  the  coil  and  secured 
l>y  the  ends  of  the  string/  The 
coil  is  then  suspended  by  some 
simple  means,  the  capped  end 
being  downward,  and  5  c.  c.  of 
the  milk  to  be  tested,  run  on  to  the  upper  part  from  a 
pipette.  The  milk  is  rapidly  absorbed  by  the  paper 
and  none  filters  through  the  cap.  It  is  then  dried  in  a 
water  oven  for  an  hour  or  two. 

Sour  milk  must  be  weighed  and  thinned  with  a  few 
drops  of  ammonium  hydroxid  before  absorption  by  the 
paper. 

Heavy  filter  paper  of  good  quality,  which  yields  to 
ether  only  a  milligram  or  less,  may  also  be  employed, 
as  suggested  by  Thomson.  One  end  of  the  strip  is 
fastened  to  some  convenient  support,  and  the  other  be- 
tween the  fingers.  The  paper  being  kept  horizontal, 
5  c.c.  of  the  milk  are  taken  in  a  pipette,  and  distributed 
evenly  over  it,  the  end  of  the  pipette  being  wiped  on  a 
part  left  dry  for  the  purpose.  It  is  dried  by  passing  to 


WERNER-SCHMID  METHOD. 


23 


and  fro  a  short  distance  over  a  Bunsen  flame,  or  better, 
by  suspending  it  in  front  of  a  stove. 

Werner-Schmid  Method.— This  is  a  very  satis- 
factory and  rapid  method  for  the  determination  of  fat 
and  is  especially  suitable  for  sour  milk. 

10  c.  c.  of  the  milk  are  measured  into  a  long  test- 
tube  of  50  c.  c.  capacity,  graduated  to  tenths  c.  c.,  and 
ten  c.  c.  of  strong  hydrochloric  acid  added,  or  the 
milk  may  be  weighed  in  a  small  beaker  and  washed 
into  the  tube  with  the  acid.  After  mixing,  the  liquid 
is  boiled  one  and  a  half  minutes,  or  the  tube  may  be 
corked  and  heated  in  the  water  bath  from  five  to  ten 
minutes,  until  the  liquid  turns  dark  brown.  It  must 
not  be  allowed  to  turn  black.  The  tube  and  contents 
are  cooled  in  water,  30  c.  c.  of  well 
washed  ether  added,  shaken,  and 
allowed  to  stand  until  the  line  of  acid 
and  ether  is  distinct.  The  cork  is  tak- 
en out,  and  a  double  tube  arrange- 
ment, like  that  of  the  ordinary  wash- 
bottle,  inserted.  The  stopper  of  this 
should  be  of  cork  and  not  of  rubber, 
since  it  is  difficult  to  slide  the  glass 
tube  in  rubber,  and  there  is  a  possi- 
bility, also,  of  the  ether  acting  on 
the  rubber  and  dissolving  it.  The 
lower  end  of  the  exit  tube  is  adjust- 
ed so  as  to  rest  immediately  above 
the  junction  of  the  two  liquids.  The 
ethereal  solution  of  fat  is  then  blown 


24  ANALYTICAL  PROCESSES. 

out,  and  received  in  a  weighed  flask.  Two  j  more  por- 
tions of  ether,  10  c.  c.  each,  are  shaken  with  the  acid 
liquid,  blown  out  and  added  to  the  first.  The  ether  is 
then  distilled  off,  and  the  fat  dried  and  weighed  as 
above. 

Lactocrite  Method. — In  response  to  the  demand 
for  a  method  for  fat  determination,  capable  of  affording 
fairly  accurate  results  in  the  hands  of  dairymen  and 
others  unskilled  in  analytical  operations,  many  process- 
es have  been  devised,  among  which,  those  depending 
upon  the  use  of  centrifugal  machines  have  proved 
most  satisfactory.  The  lactocrite  of  De  Laval  is  of  this 
class.  The  following  description  of  the  machine  and  its 
use  is  given  by  H.  Faber  (Analyst,  XII,  p.  6,)  "The  appa- 
ratus itself  consists  of  a  strong  round  steel  disc  on  a  spin- 
dle, and  test  boxes  of  platinum-plated  brass,  with  grad- 
uated glass  tubes.  10  c.  c.  of  the  sample  of  milk  to 
be  tested  are  run  into  a  small  test  glass,  afterwards  10 
c.  c.  of  glacial  acetic  acid,  containing  5  per  cent,  by  vol- 
ume of  concentrated  sulfuric  acid,  are  run  into  the 
same  glass,  which  is  closed  with  a  perforated  cork- 
stopper,  in  which  is  inserted  apiece  of  glass  tube;  this 
serves  to  prevent  a  concentration  of  the  contents  of  the 
test  glass  during  the  boiling.  In  a  water  bath,  arrang- 
ed to  hold  twelve  test  glasses,  these  are  heated  by 
steam  or  gas  for  seven  or  eight  minutes,  after  which 
time  the  casein  has  been  completely  dissolved,  while 
the  liquid  has  acquired  a  slight  violet  tinge.  The  next 
step  is  to  charge  the  test  boxes.  These  consist  of  a 


LACTOCRITE    METHOD.  25 

cup  in  which  a  perforated  stopper  fits  tightly.  The 
stopper  holds  the  graduated  glass  tube.  As  the  fat  in 
the  milk  after  boiling  with  acid  has  a  great  tendency 
to  rise,  the  test-glass  must  be  well  shaken  before  its 
contents  are  poured  into  the  cup,  and  when  this  is  filled 
the  stopper  must  be  immediately  pressed  down  in  it 
whereby  any  excess  of  the  mixture  will  escape  through 
the  glass  tube,  and  the  test-box  is  filled  completely. 
After  the  test-boxes  have  been  charged  in  this  way,  they 
are  ready  to  be  placed  in  the  disc  which  will  hold 
twelve  at  a  time.  The  disc,  which  before  use  must  be 
heated  to  about  110°  F.  by  being  placed  in  water  of 
this  temperature,has  twelve  cylindrical  holes  bored  from 
a  cavity  on  the  top,  radiating  and  a  little  sloping,  In 
these  the  test-boxes  are  placed  (if  less  than  twelve  test- 
boxes  are  used  there  should  always  be  an  even  number 
placed  so  as  not  to  disturb  the  equilibrium)  and  the 
cavity  is  filled  with  water,  which  will  keep  the  liquid  in 
the  test-boxes  from  being  pressed  out  by  the  centrifu- 
gal force.  The  disc,  which  fits  any  stand  of  a  Laval 
separator,  is  now  made  to  revolve  for  three  or  four 
minutes  at  ordinary  speed  (6000  revolutions  in  the 
minute).  When  it  is  again  at  rest,  the  test-boxes  are 
drawn  out  and  the  column  of  fat  on  the  graduated  tube 
is  read  off,  the  divisions  indicating  immediately  tenths 
per  cent,  of  butter-fat  by  weight." 

The  results  obtained  with  whole  milks  are  very  sat- 
isfactory, being  within  one-tenth  per  cent,  and  less,  of 
those  furnished  by  the  Adams'  process.  With  milks 
poor  in  fat,  however,  the  results  are  low  and  it  fails  to 

c 


26 


ANALYTICAL    PROCESSES. 


indicate  any  fat  whatever  in  milks  which  contain  less 
than  about  .5  per  cent.  By  substituting  for  the  above 
mixture  of  sulfuric  acid  and  acetic  acid,  one  made 
of  hydrochloric  acid  and  lactic  acid  in  the  same  por- 
portion  (i  to  1 9)  this  objection  is  overcome.  The  pro- 
cess so  modified  has  been  patented  by  the  Separator 
Company  of  Stockholm. 

Leffmann-Beam  Method. — The  cost  of  the  lacto- 
crite  has  prevented  its  general  adoption.  The  follow- 
ing method  devised  by  ourselves,  can  be  applied  much 
more  cheaply  both  as  regards  the  original  cost  of  the 
apparatus,  and  of  the  chemicals  required  for  the  test— 
the  latter  being  no  inconsiderable  item  when  many  tests 
are  made  with  the  lactocrite.  The  manipulation  is  also 
very  much  simplified,  the  entire  operation  being  per- 
formed in  one  test-bottle,  and  the  use  of  the  water-bath 
avoided. 

The  annexed  cuts  show  the  form  of  centrifugal  ma- 
chines, bottles  and  other  accessories  used.  Machines 
arranged  for  either  two,  four,  six,  eight  or  twelve  bot- 
tles are  manufactured.  The  process  is  covered  by  pa- 


3CC  PIPETTE. 


LEFFMANN-BEAM    METHOD. 


27 


tent,  in  the  United  States,  which  has  been  assigned  to 
J.  E.  Lonergan,  of  Philadelphia. 


The  test-bottles,  the  form  of  which  is  shown 
in  the  cut,  have  a  capacity  of  about  30  c.  c., 
and  are  provided  with  a  graduated  neck,  each 
division  of  which  represents  one-tenth  per 
cent  by  weight  of  butter-fat. 

15  c.  c.  of  the  milk  are  measured  into 
the  bottle,  3  c.  c.  of  a  mixture  of  equal  parts  of 
amyl  alcohol  and  strong  hydrochloric  acid  added, 
mixed,  the  bottle  filled  nearly  to  the  neck  with 
concentrated  sulfuric  acid  and  the  liquids  mixed 
by  holding  the  bottle  by  the  neck  and  giving  it 
a  gyratory  motion.  The  neck  is  now  rilled  to  about 


28  ANALYTICAL    PROCESSES. 

the  zero  point,  with  a  mixture  of  sulfuric  acid 
and  water  prepared  at  the  time.  It  is  then  placed  in 
the  centrifugal  machine,  which  is  so  arranged  that  when 
at  rest  the  bottles  are  in  a  vertical  position.  If  only 
one  test  is  to  be  made,  the  equilibrium  of  the  machine  is 
maintained  by  means  of  a  test-bottle,  or  bottles,  filled 
with  a  mixture  of  equal  parts  of  sulfuric  acid  and  wa- 
ter. After  rotation  for  from  one  to  two  minutes,  the  fat 
will  collect  in  the  neck  of  the  bottle  and  the  percent- 
age may  be  read  off.  It  is  convenient  to  use  a  pair 
of  dividers  in  making  the  reading.  The  legs  of  these  are 
placed  at  the  upper  and  lower  limits  respectively  of  the 
fat,  allowance  being  made  for  the  meniscus;  one  leg  is 
then  placed  at  the  zero  point  and  the  reading  made  with 
the  other.  The  results  do  not  differ  from  those  obtain- 
ed by  the  Adams'  process  by  more  than  one-tenth  per 
cent.,  and  are  generally  even  closer. 

Cream  is  to  be  diluted  to  exactly  ten  times  its  volume, 
the  specific  gravity  taken,  and  the  liquid  treated  as  a 
milk.  Since  in  the  graduation  of  the  test-bottles  a 
specific  gravity  of  1030  is  assumed,  the  reading  must 
be  increased  in  proportion. 

A  more  accurate  result  may  be  obtained  by  weighing 
in  the  test-bottle  about  2  c.  c.  of  the  cream  and  di- 
luting to  about  15  c.  c.  The  reading  obtained  is  to  be 
multiplied  by  15.45  and  divided  by  the  weight  in  grams 
of  cream  taken. 

Calculation  Method Several  investigators   have 

proposed  formulae  by  which  when  any  two  of  the  data, 


CALCULATION    METHOD.  29 

sp.  gr.,  fat  and  total  solids  are  known,  the  third  can 
be  calculated.  Since  the  determination  of  the  fat  and 
specific  gravity  can  be  accurately  made  by  rapid  and 
simple  methods,  the  formulae  become  very  servic- 
able  and  should  always  be  used  to  check  the  results. 
That  of  Hehner  and  Richmond  is  now  exclusively  used, 
having  been  based  on  extensive  observation  and  perfect 
processes  of  fat  extraction. 

The  formula  is  as  follows: — 

F=  .859  T  — .2186  G 

in  which  F  represents  the  fat,  T  the  total  solids  and 
G  the  specific  gravity.  This  formula  will  suffice  for 
ordinary  milks,  but  for  poor  skim  milks  it  has  been 
found  necessary  to  modify  it  as  follows  : — 

F=  .859  T-. 2186  G-.OS  (-  -2.5) 

This  correction  is  to  be  applied  only  when  G  divi- 
ded by  T  exceeds  2.5. 

In  these  formulae,  G  represents  the  last  two  units  of 
the  specific  gravity  and  any  decimal.  Thus,  if  the 
observed  specific  gravity  be  1029.5,  G  will  be  29.5. 

Tables  calculated  from  these  formulae  will  be  found 
in  the  appendix  so  that  by  reference  to  the  proper  col- 
umns, the  third  datum  may  be  obtained  at  once. 
A  still  more  ready  means  of  applying  the  formula  is  by 
the  use  of  Richmond's  slide- rule.  This  has  three 
scales,  two  of  which,  for  fat  and  total  solids  respectfully, 


30  ANALYTICAL     PROCESSES. 

are  marked  on  the  body  of  the  rule,  while  that  for  the 
specific  gravity  is  placed  on  the  sliding  portion. 

The  divisions  are  as  follows : — 

Total  solids     .     .     .     .     I  inch  divided  into  tenths 

Fat I  164  inches    " 

Specific  Gravity  .       0.254       "         "         "      halves 

The  rule  is  employed  by  adjusting  the  arrow  point 
to  the  graduation  corresponding  to  the  fat  found,  when 
the  figure  for  the  total  solids  will  coincide  with  that  for 
the  observed  specific  gravity.  This  instrument  does 
not  take  into  consideration  the  necessary  correction  for 
poor  skim  milks,  but  the  error  from  this  cause  will  in 
no  case  exceed  .08  per  cent  of  fat  and  may  usually  be 
disregarded. 

TOTAL  PROTEIDS. 

This  determination  is  best  made  by  calculation  from 
the  figure  for  total  nitrogen  obtained  by  Gunning's 
modification  of  Kjeldahl's  process.  The  reagents  and 
apparatus  required  are  as  follows  :— 

Standard  Sulfuric  Acid. — This  should  be  about  dec- 
inormal,  the  exact  value  being  determined  by  precipi- 
tating a  measured  volume  with  barium  chloride,  collec- 
ting and  weighing  the  barium,  sulfate  under  the  usual 
precautions. 

Standard  Barium  Hydroxid. — This  should  be  about 
decinormal.  The  volumetric  relation  between  this 
solution  and  the  standard  sulfuric  acid  must  be  accur- 


TOTAL    PROTEIDS.  31 

ately   determined,    employing  phenolphthalein  as  an 
indicator. 

Acid  Potassium  Sulfate  Mixture. — One  part  of 
pure  potassium  sulfate  is  heated  with  two  parts 
of  sulfuric  acid  (strictly  C.  P.)  until  the  potassium 
sulfate  is  dissolved.  The  mixture  is  semi-solid  when 
cold  but  may  be  readily  liquified  by  warming. 

Sodium  Hydroxid  Solution. — A  saturated  solution 
in  water.  The  best  grades  of  pulverized  caustic  soda 
will  suffice,  such  as  those  sold  as  concentrated  lye  for 
household  use,  e.g.  "Banner  Lye"  and  that  of  the  Green- 
bank  Alkali  Co. 

Digestion  Flask. — A  round-bottomed  short-necked 
flask  with  a  capacity  of  300  c.  c. 

Distilling  Flask. — A  flask  of  ordinary  shape,  about 
550  c.  c.  capacity,  is  fitted  by  means  of  a  rubber  stopper 
with  a  delivery  tube,  the  lower  end  of  which  projects 
slightly  below  the  stopper  and  should  be  cut  off  oblique- 
ly. The  tube  should  be  of  the  same  diameter  as  that  of 
the  condensing  tube  noted  below  and  should  have  one  or 
two  bulbs  about  four  centimeters  in  diameter  to  prevent 
the  carrying  over  of  sodium  hydroxid  during  the  dis- 
tillation. 

Copper  flasks  are  now  manufactured  for  this  pur- 
pose and  will  be  found  convenient  and  economical. 

Condenser. — The  condensing  tube  must  be  of  block 
tin  of  an  external  diameter  of  about  one  centimeter. 
At  least  30  centimeters  of  its  length  should  be  in  con- 
tact with  the  cooling  water.  The  junction  of  the  glass 


32  ANALYTICAL  PROCESSES. 

and  tin  tube  is  made  by  a  short  close-fitting  rubber 
tube,  and  the  tubes  are  so  bent  as  to  slope  towards  the 
distilling  flask.  The  lower  end  of  the  tin  tube  is  con- 
nected by  a  short  rubber  tube  with  a  glass  bulb  tube 
which  dips  into  an  Erlenmeyer  flask  of  about  300  c.  c 
capacity. 

5  c.  c.  of  the  milk  are  weighed  or  measured  into  the 
flask  and  evaporated  to  dryness  over  the  water-bath. 
30  c.c.  of  the  acid  potassium  sulfate  mixture  are  added 
and  heated  over  the  Bunsen  burner.  At  first,  frothing 
occurs  and  white  fumes  escape,  consisting  chiefly  of 
water  vapor.  To  prevent  loss  of  acid,  the  neck  of  the 
flask  is  now  fitted  with  a  funnel  which  is  covered  with 
a  watch  glass.  This  will  cause  the  acid  to  condense 
and  run  back  into  the  flask.  The  operation  is  finished 
when  the  liquid  is  colorless,  which  will  generally  be  the 
case  in  about  an  hour.  After  cooling,  the  contents  of 
the  flask  are  transferred  to  the  distilling  flask  by  the 
aid  of  about  200  c.  c.  of  water,  and  several  pieces  of  ig- 
nited pumice  dropped  in.  Sufficient  of  the  sodium  hy- 
droxid  solution  (about  50  c.  c.)  is  now  added  to  make 
the  mixture  strongly  alkaline.  It  should  be  poured 
down  the  side  of  the  flask  so  that  it  does  not  mix  at  once 
with  the  acid.  The  flask  is  now  connected  with  the  con- 
denser and  the  contents  mixed  by  shaking.  The 
Erlenmeyer  flask  into  which  the  distillate  is  to  be  re- 
ceived, is  charged  with  20  c.  c.  of  the  standard  sulfuric 
acid.  The  end  of  the  delivery  tube  should  dip  below 
the  level  of  this  liquid.  The  liquid  is  now  distilled 
until  the  whole  of  the  ammonia  is  driven  over. 


TOTAL    PROTEIDS.  33 

Usually  not  more  than  150  c.  c.  need  be  collected. 
The  acid  remaining  unneutralized  is  determined  by  ti- 
tration  with  the  standard  barium  hydroxid,  using  phe- 
nolphthalein  as  an  indicator,  and  the  nitrogen  distilled 
over  as  ammonia,  calculated.  The  nitrogen  figure 
multiplied  by  6.38  will  give  that  of  the  total  proteids. 


CASEIN  AND  ALBUMIN. 

20  c.  c.  of  the  milk  are  mixed  with  40  c.  c.  of  a  sat- 
urated solution  of  magnesium  sulfate  and  powdered 
magnesium  sulfate  stirred  in  until  no  more  will  dissolve. 
After  settling,  the  precipitate  of  casein  and  fat,  includ- 
ing the  trace  of  globulin,  is  filtered  and  washed  several 
times  with  a  saturated  solution  of  magnesium  sulfate. 
The  filtrate  and  washings  are  saved  for  the  determina- 
tion of  albumin.  The  filter  and  contents  are  trans- 
ferred to  a  flask  and  the  nitrogen  determined  by  the 
method  described  above.  The  nitrogen  so  found  mul- 
tiplied by  6.38  gives  the  casein. 

The  filtrate  and  washings  from  the  determination  of 
casein  are  mixed,  the  albumin  precipitated  by  a  solution 
of  tannin,  filtered  and  the  nitrogen  in  the  precipitate  de- 
termined as  above.  The  same  factor  is  used. 

On  account  of  the  difficulty  of  washing  the  pre- 
cipitated casein,  we  prefer  to  proceed  as  follows : 
20  c.  c.  of  the  milk  are  mixed  with  saturated  mag- 
nesium sulfate  solution  and  the  powdered  salt  added 
to  saturation.  The  mixture  is  washed  into  a  graduated 
measure  with  a  small  amount  of  the  saturated  solution, 


34  ANALYTICAL    PROCESSES. 

mixed,  the  volume  noted,  and  allowed  to  stand 
until  the  separation  takes  place.  The  liquid  is  then 
filtered,  as  much  as  possible  of  the  clear  portion  being 
drawn  off  with  a  pipette,  and  passed  through  the 
filter.  An  aliquot  portion  of  the  filtrate  is  taken, 
the  albumin  precipitated  by  a  solution  of  tannin,  and 
the  nitrogen  in  the  precipitate  determined  as  above. 

The  casein  is  found  by  subtracting  the  figure  for  albu- 
min from  that  for  total  proteids. 

The  Ritthausen  Method   for  Total  Proteids.— 

This  method  depends  on  the  precipitation  of  the 
albuminoids  by  means  of  copper  sulfate  and  sodium 
hydroxid.  It  is  applicable  only  to  fully  developed 
milks  ;  the  proteids  of  colostrum  are  only  partially  pre- 
cipitated. The  following  reagents  are  required. 

Copper  Sulfate  Solution. — 34.64  grams  of  pure  crys- 
talized  copper  sulfate  are  dissolved  and  made  up  to 
500  c.  c. 

Sodium  Hydroxid  Solution. — About  1 2  grams  are  dis- 
solved in  500  c.  c.  of  water. 

10  grams  of  the  milk  are  placed  in  a  beaker,  diluted 
with  100  c.  c.  of  distilled  water,  5  c.  c.  of  copper  sul- 
fate solution  added  and  thoroughly  mixed.  The, 
sodium  hydroxid  solution  is  then  added  drop  by  drop 
with  constant  stirring,  until  the  precipitate  settles 
quickly  and  the  liquid  is  neutral,  or  at  most  very  feebly 
acid.  An  excess  of  alkali  will  prevent  the  precipita- 
tion of  some  of  the  proteids. 


TOTAL   PROTEIDS.  35 

The  reaction  should  be  tested  on  a  drop  of  the  clear 
liquid,  withdrawing  it  by  means  of  a  rod,  taking  care 
not  to  include  any  solid  particles.  When  the  operation  is 
correctly  performed,  the  precipitate  which  includes  the 
fat,  settles  quickly,  and  carries  down  all  of  the  copper. 
It  is  washed  by  decantation  with  about  100  c.  c.  of  wa- 
ter, and  collected  on  a  filter  (previously  dried  at  265°  F 
and  weighed  in  a  weighing  bottle).  The  portions  adher- 
ing to  the  sides  of  the  beaker  are  dislodged  with  the 
aid  of  a  rubber-tipped  rod.  The  contents  of  the  filter 
are  washed  with  water  until  250  c.  c.  are  collected, 
which  are  mixed  and  reserved  for  the  determination  of 
the  sugar  as  described  below.  The  water  in  the  pre- 
cipitate is  removed  by  washing  once  with  strong  al- 
cohol, and  the  fat  by  six  or  eight  washings  with  ether. 
The  Soxhlet  apparatus  may  be  used  for  this  purpose. 
The  washings  being  received  in  a  weighed  flask,  the 
determination  of  the  fat  may  be  made  by  evaporating 
the  ether  with  the  usual  precautions. 

The  residue  on  the  filter,  which  consists  of  the  pro- 
teids  in  association  with  copper  hydroxid.is  washed  with 
absolute  alcohol  which  renders  it  more  granular,  and 
then  dried  at  265 °F.  in  the  air  bath.  It  is  weighed  in 
a  weighing  bottle,  transferred  to  a  porcelain  crucible, 
incinerated,  and  the  residue  again  weighed.  The 
weight  of  the  filter  and  contents,  less  that  of  the  filter 
and  residue  after  ignition,  gives  the  weight  of  the  pro- 
teids.  The  results  by  this  method  are  slightly  high, 
owing  to  the  fact  that  the  copper  hydroxid  does  not 
become  completely  converted  into  copper  oxid  at  265° 


36  ANALYTICAL    PROCESSES. 

but  the  error  so  introduced  is  not  great  and  may  usual- 
ly be  disregarded. 

SUGAR. 

The  following  method  due  to  Soxhlet,  employs  a 
Fehling's  solution,  made  as  required,  by  mixing  equal 
parts  of  the  following  solutions  :— 

Copper  Sulfate  Solution. — 34.64  grams  of  pure  crys- 
tallized copper  sulfate  are  dissolved  in  distilled  water 
and  made  up  to  500  c  c. 

Alkaline  Tartrate  Solution.— \J  ^  grams  of  pure  sodium 
potassium  tartrate,  and  5  I  grams  of  sodium  hydroxid 
of  good  quality,  are  dissolved  and  made  up  to  500  c.  c. 

100  c.  c.  of  the  mixed  nitrate  from  the  precipitated 
proteids  are  brought  to  boiling,  in  a  beaker,  50  c.  c.  of 
boiling  Fehling's  solution  added,  and  the  boiling  con- 
tinued for  six  minutes.  The  precipitate  is  allowed  to 
settle  for  a  short  time,  and  the  supernatant  liquid  pour- 
ed through  a  filter.  About  50  c.  c.  of  boiling  water  are 
added  to  the  residue,  and  the  heating  continued  for  a 
minute  or  two.  The  precipitate  is  then  conveyed  to 
the  filter,  washed  with  boiling  water,  with  alcohol  and 
finally  with  a  small  quantity  of  ether.  The  filter  and 
contents  are  dried  in  the  water  oven,  the  precipitate  re- 
moved to  a  tared  porcelain  crucible,  the  filter  held  over 
the  crucible  and  burnt  to  ash,  which  is  added  to  the 
precipitate,  and  the  cuprous  oxid  converted  into  cupric 
oxid  by  strong  ignition  for  five  or  ten  minutes  over  the 
Bunsen  burner. 

The  amount  of  copper  reduced  under  the  conditions 
detailed  above  is  not  directly  proportional  to  the  milk 


SUGAR. 


37 


sugar  present.  The  following  table  shows  the  amounts 
of  milk  sugar  (Q2  H22  On  -f  H2  O)  equivalent  to 
given  weights  of  cupric  oxid.  The  volumes  of  Feh- 
ling's  solution  and  sugar  solution,  must  conform 
strictly  to  the  figures  given  above. 


*M 

•  •-  °  -v 

. 

o^ 

2 

*ti 

SB 

"2 

o  8  "M 

d 

0 
2 

§  S  o 
|f« 

p 

BQ 

H 

O 
w 

i  •»« 

1 

i, 

ill 

•3 

"C 

ft 

r?  ^  O. 

M 

o 

2  * 

S 

5 

5  o 

i 

.4916     0.85 

0.300  ;     .3281 

0.78 

0.195 

.4844 

0.85 

0.295  ;     .3201 

0.78 

0.190 

.4771 

0.85 

0.290  1     .3121 

0.78 

0.185 

.4697 

0.85 

o  285     .3040 

0.78 

0.180 

.4625 

0.85   0.280 

.2959 

0.78 

0.175 

•4552 

0.85   0.275 

.2880 

0.78 

0.170 

•4475 

o  81  i    0.270 

.2798 

0.78 

0.165 

.4398     0.81 

0.265       .2718 

0.78 

o.r6o 

.4322     0.81 

0.260 

.2636 

0.78 

0.155 

.4245  ;   0.81 

0.255 

.2554 

0.78 

0.150 

.4169 

0.78 

0.250       .2473 

0.76 

0.145 

.4089 

0.78 

0.245 

.2391 

0.76 

0.140 

.4007 

0.78 

0.240 

.2308 

0.76 

0-135 

•3927 

0.78 

0.235 

.2227 

0.76 

0.130 

.3846 

0.78 

0.230 

.2146 

0.76  i  0.125 

.3766 

0.78 

0.225 

•2063 

o.75 

O.  1  2O 

•3685 

0.78 

O.22O 

.1979 

0.75 

0.115 

.3604 

0.78 

0.215 

.1897 

0.75 

O.IIO 

•3524 

0.78 

O.2IO 

.1814 

o.75 

0.105 

•3443 

0.78 

0.205 

•  1731 

0-75 

O.  IOO 

•3363 

0.78 

O.2OO 

The  determination  of  sugar  may  also  be  made  by 
means  of  the  polarimeter  after  removal  of  the  fat  and 
proteids.  This  may  be  effected  by  means  of  a  nitric 
acid  solution  of  mercuric  nitrate  as  suggested  by 
Wiley. 

The  mercuric  nitrate  solution  is  prepared  by  dissolv- 
ing mercury  in  an  equal  weight  of  nitric  acid  of 


-38  ANALYTICAL     PROCESSES. 

1.42  sp.  gr.  and  adding  to  the  solution  an  equal  bulk 
of  water. 

60  c.  c.  of  the  milk  are  placed  in  a  100  c.  c.  flask 
and  I  c.  c.  of  the  mercuric  solution  added.  The  flask 
is  filled  to  the  mark  with  water,  well  shaken  and  the 
liquid  filtered  through  a  dry  filter.  The  filtrate,  which 
will  be  perfectly  clear,  may  be  examined  in  the  polar- 
imeter.  Several  readings  should  be  made  and  the 
average  taken. 

It  is  to  be  noted  that  the  actual  volume  of  the  sugar 
containing  solution  is  looc.  c.,  less  the  space  occupied 
by  the  precipitated  proteids  and  fat.  The  volume  of 
fat  is  found  by  multiplying  the  weight  in  grams  by 
1.075  and  the  proteids  by  multiplying  the  weight  by  .8 

For  example:  — 

Sp.  Gr.  of  milk  1030,  Fat  4  per  cent,  Proteids  4  per  cent. 
Milk  taken  =  60  X  J-O3  =  61.80  gms. 
The  weight  of  fat  =  4  per  cent   of  61.80  =  2,47  gms. 
The  weight  of  proteids  =  4  per  cent,  of  61.80  =  2.47  gms. 
The  volume  of  fat  =  2.47  X  i-<>75  =  2.65  c.  c. 
The  volume  of  proteids  =  2.47  X  -8  =  1.97  c.  c. 
The  bulk  of  the  sugar  containing  liquid  is  therefore 
100  —  (2.65  +  1.97)   =  95.38  c.  c. 

In  order  to  avoid  the  calculation  involved  in  taking 
60  c.  c.  of  the  milk  as  given  above,  an  amount  may  be 
employed  which  is  a  simple  multiple  of  the  standard 
quantity  to  be  used  in  the  polarimeter  at  hand- 
Thus,  for  instruments  adjusted  so  that  16.19  grams  of 
.sucrose  (20.56  grams  of  milk  sugar)  in  100  c.  c.  of  the 


SUGAR.  39 

solution  produce  a  rotation  of  100  degrees  on  the 
per  cent,  scale,  61.68  grams  (20.56  X  3)  may  be 
weighed  out  directly  for  the  purpose  and  made 
up  to  100  c.  c.  plus  the  volume  occupied  by  the 
fat  and  proteids,  the  latter  being  calculated  as  above. 
The  sugar  containing  liquid  will  then  be  exactly 
loo  c.  c.,  and  the  reading  on  the  polarimeter  divided 
by  three  will  give  the  percentage  of  hydrated  milk 
sugar  direct,  if  a  200  mm.  tube  be  employed.  With 
a  400  mm.  tube  or  500  mm.  tube  the  reading  is 
to  be  divided  by  6  or  7.5  respectively. 

Polarimeter s. — A  discussion  of  the  construction  of 
the  various  forms  of  polarimeters  and  of  the  optical 
principles  involved,  would  be  beyond  the  scope  of  this 
work.  It  may  be  stated  that  the  so  called  half-shadow 
instruments,  for  use  with  the  sodium  flame,  are  the 
most  satisfactory.  They  are  so  arranged,  by  the  use 
of  a  semicircle  of  thin  quartz,  that  the  field  is  divided 
into  semicircles  which  are  equally  illuminated  when 
the  instrument  registers  zero.  On  the  introduction 
of  the  tube  carrying  the  sugar  solution,  the  illumina- 
tion becomes  unequal  and  the  angular  rotation  of  the 
analyser  which  is  required  to  restore  the  original  con- 
dition, measures  the  rotation  which  has  been  caused 
by  the  sugar.  Most  instruments  are  furnished  with 
two  scales,  one  showing  the  rotation  in  angular  de- 
grees and  the  other  expressing  per  cent,  directly. 
The  latter  reads  to  100  when  a  certain  fixed  quantity 
of  the  material  has  been  dissolved  in  water  and 
diluted  to  100  c.  c. 


40  ANALYTICAL    PROCESSES. 

The  specific  rotatory  power  of  a  substance  is  the 
amount  of  rotation  of  the  plane  of  polarized  light,  in 
angular  degrees,  produced  by  a  solution  containing 
one  gram  of  the  substance  in  one  c.  c.,  examined  in  a 
column  one  decimeter  long. 

It  is  expressed  by  the  following  formula  in  which 

vS  is  the  specific  rotatory  power  for  light  of  wave 
length  corresponding  to  the  D  line  of  the  spectrum 
(sodium  flame). 

a  is  the  angular  rotation  observed, 

c  is  the     concentration    of    the    solution    (weight 
in  grams,  in  100  c.  c.  of  the  liquid)  and 

/  is  the  length  of  the  tube  in  decimeters. 
100  a 

=  7~x7 

Calculation  of  the  amount  of  sugar  corresponding 
to  the  observed  rotation  may  be  made  by^substitution 
in  the  formula. 

The  sodium  flame  is  most  conveniently  obtained  by 
means  of  a  bead  of  sodium  carbonate,  on  platinum 
wire,  heated  in  the  flame  of  the  Bunsen  burner. 

The  specific  rotatory  power  of  milk  sugar  is  unaffect- 
ed by  the  concentration  within  the  limits  encountered 
in  ordinary  analytical  work.  It  is  slightly  affected  by 
temperature,  being  decreased  by  about  .042  angular 
degree  for  each  successive  rise  of  one^'degree.  The 
specific  rotatory  power  at  68°  F.  is  52*5°  when  obsev- 
ed  by  the  sodium  flame. 

Birotatton. — When  freshly  dissolved  in  cold  water, 
milk  sugar  shows  a  higher  rotation  than  that  given 


ADULTERANTS.  41 

above.  By  standing,  or  immediately  on  boiling,  the 
rotatory  power  falls  to  the  point  mentioned.  In  pre- 
paring solutions  from  the  solid  milk  sugar,  care  must 
be  taken  to  bring  them  to  the  boiling  point,  previous 
to  making  up  to  a  definite  volume.  This  precaution 
is  unnecessary  when  operating  upon  milk. 

MIIvK  ADULTERANTS. 

Water. — The  addition  of  water  to  milk  is  usually 
detected  by  the  diminution  in  the  amount  of 
solids.  Since  nitrates  are  absent  from  normal  milk,  and 
almost  invariably  present  in  surface  and  subsoil  waters,  it 
may  be  possible  to  detect  the  addition  of  water  by  the 
application  of  one  of  the  delicate  tests  for  nitrates.  The 
value  of  this  method  is  considerably  impaired  by  the 
fact  that  small  amounts  of  nitrates  may  be  introduced 
into  the  milk  by  the  water  used  in  rinsing  the  cans. 
Nevertheless,  the  presence  of  notable  quantities  of  ni- 
trates will  be  ground  for  grave  suspicion.  The  test  is 
applied  as  follows : — Several  grains  of  diphenylamin 
are  placed  in  a  test-tube  and  dissolved  in  two  or  three 
c.  c.  of  strong,  pure  sulfuric  acid.  A  small  quantity  of 
milk  is  then  added  carefully,  so  as  to  form  a  layer  on 
the  surface  of  the  acid.  If  nitrates  be  present,  a  blue 
color  is  formed  at  the  junction  of  the  two  layers. 

With  any  given  sample  of  milk,  addition  of  water  de- 
creases the  gravity,  while  abstraction  of  fat  increases  it. 
It  is  possible,  therefore,  by  carrying  out  both  methods 
of  adulteration  carefully,  to  maintain  the  same  gravity 
as  in  the  original  sample,  so  that  this  datum  alone  will 

D 


42  ANALYTICAL    PROCESSES. 

not  suffice  to  detect  adulteration.  Taken  in  conjuction 
with  either  the  figure  for  fat  or  for  total  solids,  the 
specific  gravity  becomes  of  direct  value,  and  furnishes 
a  means  for  determining,  by  calculation,  the  remaining 
datum  . 

For  milk  control  in  dairies,  etc.,  it  will  suffice  to  take 
the  specific  gravity  by  the  lactodensimeter  (see  page  16) 
and  the  fat  by  the  Leffmann-Beam  method.  From  the 
figures  thus  obtained  the  total  solids  can  be  ascertained 
by  Hehner  &  Richmond's  table  (Table  B)  or  Rich- 
mond's slide-rule. 

Various  substances  are  added  to  milk  to  conceal 
adulteration  or  inferiority  in  quality.  The  most  fre- 
quently employed  are  coloring  matters.  Sugar,  salt, 
starch  and  calf's  brain  have  been  added  to  milk,  but 
are  of  infrequent  occurence.  It  has  occasionally 
been  stated  that  chalk  has  been  added,  but  this  is  ob- 
viously unlikely.  The.  coloring  matters  most  frequently 
employed  are  annatto,  caramel,  saffron,  carotin  and 
occasionally  turmeric  and  certain  coal-tar  colors. 

Annatto  is  easily  detected  by  rendering  the  sample 
slightly  alkaline  by  the  addition  of  sodium  acid  carbon- 
ate, immersing  in  it  a  slip  of  filter  paper  and  allow- 
ing it  to  remain  over  night.  The  presence  of  annatto 
will  be  indicated  by  a  distinct  reddish-yellow  tinge 
to  the  paper. 

Coal-tar  colors  are  detected  by  adding  to  the  milk 
ammonium  hydroxid  and  allowing  a  piece  of  white 
wool  to  remain  in  it  over  night.  The  dye  is  taken  up 
by  the  wool,  which  acquires  a  yellow  tinge.  When 


ADULTERANTS.  43 

milk  contains  Martius'  yellow,  ammonium  hydroxid 
intensifies  the  color  and  hydrochloric  acid  bleaches  it. 
Starch  may  be  detected  by  the  blue  color  developed 
on  the  addition  of  solution  of  iodin  to  the  milk,  which 
has  previously  been  heated  to  the  boiling  temperature 
and  then  cooled.  Starch  is  very  often  added  to  ice- 
cream and  similar  articles. 

Salt  and  Cane  sugar  are  occasionally  added  to  milk 
that  has  been  diluted  with  water.  The  former  is  easily 
detected  by  the  taste,  the  increased  proportion  of  ash 
and  of  chlorin.  Cane  sugar  may  be  detected,  if  in  con- 
siderable quantity,  by  the  taste.  The  quantitive  de- 
termination is  made  by  the  methods  described  in  con- 
nection with  condensed  milk. 

Additions  such  as  calf's  brain,  may  be  detected  by 
microscopic  examination  of  the  milk,  or  of  the  sedi- 
ment, if  any  be  formed  on  standing. 

Antiseptic  substances  are  now  largely  employed  by 
dairymen  and  milk  purveyors,  especially  in  the  warmer 
seasons,  as  a  substitute  for  refrigeration.  Preparations 
of  boric  acid  and  borax  are  most  frequently  used  and 
are  often  sold  under  proprietary  names  which  give  no 
indication  of  their  composition.  Sodium  carbonate 
is  occasionally  used  to  prevent  coagulation  resulting 
from  slight  souring. 

Sodium  Carbonate. — The  following  method,  due  to 
E.  Schmidt,  is  stated  to  be  capable  of  detecting  one- 
tenth  of  one  per  cent,  of  sodium  carbonate,  or  of  sodium 
acid  carbonate. 


44  ANALYTICAL  PROCESSES. 

10  c.  c.  of  the  milk  are  mixed  with  an  equal  volume 
of  alcohol,  and  a  few  drops  of  a  one  per  cent,  solution 
of  rosolic  acid  added.  Pure  milk  shows  merely  a 
brownish-yellow  color,  but  in  the  presence  of  sodium 
carbonate  a  more  or  less  marked  rose-red  appears. 
The  delicacy  of  the  test  is  enhanced  by  making  a 
comparison  cylinder  with  the  same  amount  of  milk 
known  to  be  pure.  Any  considerable  addition  of  the 
salt  may  be  detected  by  the  increase  in  the  ash,  its 
marked  alkalinity  and  effervescence  with  acid. 

Benzole  Acid. — 250-500  c.  c.  of  the  sample  are 
rendered  alkaline  by  a  few  drops  of  calcium  or  barium 
hydroxid,  evaporated  to  one-fourth  bulk,  mixed  with 
sufficient  calcium  sulfate  to  make  a  pasty  mass  and 
dried  on  the  water  bath.  When  condensed  milk  is 
examined,  100—150  grams  should  be  mixed  directly 
with  sufficient  calcium  sulfate,  and  a  few  drops  of 
barium  hydroxid.  Since  the  calcium  sulfate  is  only 
employed  to  facilitate  the  drying,  it  may  be  replaced 
by  powdered  pumice  or  other  inert  material.  The  dry 
mass  is  finely  powered,  moistened  with  dilute  sul- 
furic  acid  and  then  exhausted  three  or  four  times 
with  about  twice  its  volume  of  cold  (50  per  cent.)  alco- 
hol, which  dissolves  benzoic  acid  freely,  but  only  mere 
traces  of  the  fat.  The  alcoholic  liquid  which,  in  ad- 
dition to  the  benzoic  acid,  contains  milk  sugar  and 
mineral  matter,  is  mixed  thoroughly,  neutralized  with 
barium  hydroxid  and  evaporated  to  small  volume.  The 
residue  is  acidified  with  weak  sulfuric  acid  and  extract- 
ed with  successive  small  portions  of  ether.  On  evap- 


ADULTERANTS.  45 

oration,  the  ether  leaves,  almost  pure,  the  benzoic  acid 
which  may  be  recognized  by  its  odor  and  volatility. 

Boric  Acid. — When  boric  acid  or  borates  are  not 
present  in  quantities  sufficient  to  appreciably  increase 
the  ash  of  the  sample,  the  quantitive  determination 
is  difficult.  The  qualitative  test  is  very  delicate. 
IOO  c.  c.  of  the  sample  are  rendered  alkaline  with  cal- 
cium hydroxid,  evaporated  and  ashed.  Calcium  hy- 
droxid  is  preferred  for  this  purpose  because  the  ashing 
takes  place  more  rapidly.  The  ash  is  dissolved  in  the 
smallest  possible  quantity  of  strong  hydrochloric  acid, 
the  solution  filtered  and  evaporated  to  dryness.  An 
appreciable  loss  of  boric  acid  will  not  occur.  The  res- 
idue is  moistened  with  very  dilute  hydrochloric  acid, 
mixed  with  tincture  of  turmeric  and  dried  on  the  water 
bath.  The  smallest  trace  of  boric  acid  gives  to  the 
residue  a  vermilion  or  cherry-red  tint. 

Concentrated  hydrochloric  acid  gives  with  tincture 
of  turmeric,  a  cherry-red  color,  which,  however,  disap- 
pears on  addition  of  water  and  also  becomes  brown  on 
drying,  while  the  boric  acid  color  appears  only  on  dry- 
ing and  is  not  destroyed  unless  much  water  be  added, 
or  at  the  boiling  point.  The  red  color  adheres  strongly 
to  the  vessel  and  may  be  removed  by  alcohol.  The 
flame  test  may  be  applied  to  the  residue,  but  it  is  not 
delicate. 

Quantitive  determinations  of  boric  acid  may  be 
made  by  Gooch's  method  as  described  in  analytical 
manuals.  Hehner  has  shown  that  sodium  phosphate 


46  ANALYTICAL  PROCESSES. 

may  be  advantageously  substituted  for  lime  in  this  pro- 
cess, the  details  of  the  modification  being  given  in  The 
Analyst  for  August,  1891. 

Salicylic  Acid. — 50  c.  c.  of  the  sample  are  treated 
with  acid  mercuric  nitrate  for  the  removal  of  the  fat 
and  proteids,  as  described  in  connection  with  the  deter- 
mination of  milk  sugar,  and  the  liquid  filtered.  The 
filtrate  is  shaken  violently  with  about  one  half  its  vol- 
ume of  a  mixture  of  equal  parts  of  ether  and  petroleum 
ether.  The  ethereal  liquid  is  evaporated  and  a  drop  of 
neutral  solution  of  ferric  chlorid  added  to  the  residue. 
If  salicylic  acid  be  present,  a  characteristic  violet  color 
is  developed.  The  reaction  is  very  delicate. 


DATA  FOR  MILK  INSPECTION. 

VARIATIONS  IN  COMPOSITION. 

Average  proportion  of  Solids  in  Milk. — The  most 
extensive  data  on  this  point  are  those  obtained 
by  Vieth,  a  summary  of  whose  results,  covering 
a  period  of  eleven  years,  was  published  in  The  Analyst 
of  May,  1892.  The  total  number  of  samples  was 
120,540,  and  although  some  changes  had  been  made  in 
the  methods  of  analysis  since  the  beginning  of  the 
work,  the  results  were  recalculated  so  as  to  be  strictly 
comparable.  The  averages  of  the  entire  series  were  as 
follows  : 

Fat          ....  4. 1  per  cent. 

Non-fatty  solids       .         .  8.8           " 

Total  solids     .         .         .  12.9          " 
Soxhlet  states  that  normal  cows'  milk  will  contain 
at  least 

Total  solids            .         .  12.00  per  cent. 

Non-fatty  solids     .         .  8.50           " 

Fat        ....  3.50           " 

Seasonal  variations  in  the  composition  of  milk. — 

The  diagrammatic  synopsis  of  the  results  obtained 
by  Vieth,  given  on  pages  48-49,  being  a  reproduction 
of  the  table  prepared  by  him,  shows  that  a  notable 

47 


48  Average  Composition  of  120,  540 

1881  1882  1683 


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Samples  of  Milk---P.  Vieth. 


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50  DATA    FOR    MILK    INSPECTION, 

variation  in  the  proportion  of  ingredients  occurs  during 
the  year.  The  poorest  quality  occurs  during  the  first 
half  of  the  year,  especially  in  April.  A  low  figure  is 
also  frequently  noted  about  July.  In  the  fall  the 
quality  rises,  being  highest  in  October  and  November. 

The  diagram  shows  that  the  variations  in  the  total 
solids  are  due  mainly  to  the  variations  in  fat,  but  not 
entirely,  for  an  increase  in  the  proportion  of  fat  is 
usually  attended  by  a  slight  increase  in  the  non-fatty 
solids. 

The  earlier  tendency  was  to  assign  too  high  a  limit 
for  the  non-fatty  solids,  since  this  figure  was  obtained 
by  methods  which  failed  to  extract  all  the  fat.  In 
applying,  therefore,  the  more  modern  processes,  nor- 
mal milk  will  be  found  to  yield  a  figure  for  the  non- 
fatty  solids  decidedly  below  the  extreme  limit  of  9.5  per 
cent.  Even  9  per  cent,  for  the  non-fatty  solids  is  more 
than  is  usually  present. 

While  it  may  be  permissible  in  special  cases,  such 
as  the  purchase  of  milk  under  contract,  or  in  the  oper- 
ation of  a  large  dairy,  to  reject  samples  which  yield 
below  nine  per  cent,  of  non-fatty  solids,  it  is  not 
just  to  exact  such  a  standard  for  purposes  of  pub- 
lic inspection,  and  as  a  basis  for  penal  proceedings. 
The  standard  of  the  Society  of  Public  Analysts  of 
England  (8.5  per  cent,  of  non-fatty  solids),  has  been 
found  satisfactory  in  the  large  experience  of  the  mem- 
bers of  that  body,  and  recently  Dr.  Vieth  has  ex- 
pressed himself  as  follows : 


DEFICIENT    SOLIDS.  51 

"My  object  is  by  no  means  to  raise  the  cry  that 
the  standard  adopted  by  the  Society  is  too  high;  on 
the  contrary,  I  think  it  is  very  judiciously  fixed,  but  in 
upholding  the  standard  of  purity  it  should  not  be  for- 
gotten that  the  cows  have  never  been  asked  for,  nor 
given  their  assent  to  it,  and  that  they  will  at  times  pro- 
duce milk  below  standard.  A  bad  season  for  hay- 
making is,  in  my  experience,  almost  invariably  fol- 
lowed by  a  particularly  low  depression  in  the  quality 
of  milk,  toward  the  end  of  winter.  Should  the  win- 
ter be  of  unusual  severity  and  length,  the  depression 
will  be  still  more  marked.  Long  spells  of  cold  and 
wet,  as  well  as  of  heat  and  drought,  during  the  time 
when  cows  are  kept  on  pasture,  also  unfavorably  influ- 
ence the  quality  and,  I  may  add,  quantity  of  milk." 

Deficient  solids. — The  following  are  some  instances 
of  deficiency  of  solids  in  milk  known  to  be  genuine. 

SP.    GR.  FAT  S.  N.  F.  T.    S.  ANALYST 

1029.6  3.38  7.95  11.33        C.  B.  Cochran 

1030.0  3.62  8.31  11.93  " 

1029.3  3.63  8.02  11.65  " 

.  .  .  3.99  8.36  12.35  Leffmann  &  Beam 

...  3.II  8.33  H-44     i  Monthly  Averages 

3.05  8.33  11.38     v  N.  J.  State  Agric. 

.    .    .  3.23  8.44  11.67     )  Exp.  Station 

In  a  herd  of  60  covvs,  Richmond  found  19  per  cent, 
of  the  samples  to  contain  between  8.38  and  8.50  per 
cent,  solids  not  fat. 
The  following  instances  of  unusually  rich  milk,  were 


52  DATA    FOR    MILK    INSPECTION. 

reported  in  The  Analyst,  January,  1893. 


Sp.  Gr. 

T'l  Solids 

Fat 

Ash               Analyst 

1026.6 

I9-50 

I  I.  06                  .53 

Smetham 

1027.8 

16.06 

7-37 

.72 

I03I.5 

14.98 

3.92 

de  Hailes 

Since  a  partial  creaming  takes  place  in  the  udder, 
the  first  milkings  (fore-milk)  are  poorer,  and  the  last 
milkings  (strippings)  richer  in  fat,  than  the  average 
milk.  To  insure  a  proper  sample,  the  entire  milking 
must  be  taken,  as  was  done  in  the  above  analyses. 

Variation  according  to  breed. — The  following  fig- 
ures taken  from  Bulletin  77,  (1890)  New  Jersey  State 
Agricultural  Experiment  Station,  show  the  average 
composition  of  milk  of  various  breeds  of  cattle  : 

AVERAGE  COMPOSITION  OF  MILK  FOR  EIGHT  MONTHS 


! 

PE1 

ICENT 

A.GE 

HERD. 

1 

3 

'§ 

1 

% 
1 

I 

_c 

1 

1 

Ayrshire    .     ... 
Ouernsey 

I034-I 
1035.0 

87.30 
85.52 

12.70 

14.48 

3.68 
5.O2 

3.48 
3-92 

4.84 
4.80 

0.69 
0.7s; 

Holstein-Friesian 
Jersey      . 

1032.8 
1035.3 

87.88 
85.66 

I2..I2 

3-51 
4-78 

3.28 
^.96 

4.69 
4.8s 

0.64 

Short-Hoin  .... 

1033-9 

87.55 

12-45 

3-27 

4.80 

0-73 

VARIATIONS  ACCORDING  TO  SEASON. 


53 


Variations  according  to  season. — The  following 
table  is  condensed  from  the  above  report. 


Ayrshire         Frie^an"           Jersey           Guernsey     Short-Horn 

T.   S.    Fat     T.   S.     Fat.   T.  S.    Fat.     T.   S.    Fat. 

T:   S. 

Fat; 

Mar. 

1                        i 
13-003.95     12.463.89     14.9915.36     15.295.46 

13-99 

4.69 

April 

I3-093-85     I2.393-84     I4-835-32     14-955-20 

12.76 

3.89 

May 

12-973-54     12.573.65!    13.6714.30     14.0014.57 

12.05 

3-24 

June 

12.583.42     12.993.73     13.424.08     13-864.55 

11.97 

3.23 

July 

12.723.71     11.443.11     13.464.13     i3.85J4.54 

11.89 

3.28 

Aug. 

13.08407    11.383.05     13.604.22     13.934.81 

1  2.  08 

3-56 

Sept. 

11.853.26    11.673.23'-  15005.08     14.675.22 

12.24 

3-47 

Oct. 

12.273.60    12083.55     15.75  5-7*'    15-285.78 

I2.6l 

3.82 

Milk  Standards. — Many  efforts  have  been  made  to 
establish  a  minimum  for  the  composition  of  normal 
milk,  with  a  view  to  prevent  adulteration.  Standards 
proposed  some  years  back,  requiring  a  high  proportion 
of  non-fatty  solids,  were  based  upon  analyses  by 
methods  which  fail  to  extract  the  whole  of  the 
fat  from  the  milk  residue.  The  Society  of  Public 
Analysts  of  England  formerly  used  a  standard  of  9  per 
cent,  non-fatty  solids  and  2.5  per  cent,  fat,  but  when 
the  improved  method  of  analysis  was  adopted,  altered 
the  standard  to  the  figures  given  in  the  table.  The 
following  are  some  of  the  standards  which  have  been 
adopted  : 


DATA    FOR    MILK    INSPECTION. 


State,  City,  etc. 


Percentage  by  Weights  of  Solids. 


Non  -fatty       Fat 


Total 


Pennsylvania,  1885,     .     .     . 

9.50        3.00 

12.50 

New  York,  1884,          .     .     . 

9.00        3.00 

I2.OO 

New  Jersey,  1882,         .     . 

9.00        3.00 

I2.OO 

Massachusetts,  1886,  .     .     . 

9.30        3.70 

13.00 

Minnesota,  1889,    ....  9.50        3.50 

Columbus,  Ohio,     ....  9-375        3'125 

Baltimore,  Md. ,      .     , 

Denver,  Col., 

I/ansing,  Mich., 

Madison,  Wis., 

Burlington,  Vt.,      .     , 

Des  Moines,  Iowa,     .     .     .       .... 

Portland,  Oregon,        

Omaha,  Nebraska,     ...       ;     3.00 

U.  S.  Treasury  Department,  9.50        3.50 

Philadelphia,  1890,  Ordinance,  8.50        3.50 

Society  of  Public  Analysts  of 

England,         ....  8.50   j     3.00 


3.00 
3.00 
3-50 
3-50 


p&  }»•<*> 

13.00 

12.50 

12.00 
12.00 
12.50 

12.50 

I3-I3 
12.00 
12. OO 
I3.OO 
12.00 

11.50 


SANITARY   RELATIONS. 

Although  questions  of  the  food  value  and  the  whole- 
someness  of  milk  are  scarcely  germain  to  this  work,  yet 
several  practical  points  of  comparatively  recent  devel- 
opement  are  intimately  connected  with  the  work  of  the 
milk  analyst  and  need  some  discussion.  It  is  now  well 
recognized  that  the  dairy  is  an  important  factor  in  the 


SANITARY    RELATIONS.  55 

distribution  of  disease,  the  influence  taking  place 
through  several  channels. 

In  the  first  place,  dairy  cattle  are  subject  to  several 
infectious  diseases  which  are  communicable  to  man  and 
virulent  in  their  effects.  The  most  important  of  these  is 
tuberculosis.  The  etiology  of  this  affection  is  now  clear. 
It  is  dependent  on  the  development  of  a  minute  organ- 
ism. The  tendency  at  the  present  time  is  to  the  view 
that  the  keeping  of  dairy  cattle  is  a  fruitful  cause  of  the 
spread  of  this  disease.  The  specific  germ  of  tuberculo- 
sis may  be  conveyed  both  in  meat  and  milk  and  since 
the  infection  of  the  animal  is  not  always  recognised 
promptly,  a  most  insidious  source  of  danger  exists. 
Other  infectious  and  dangerous  diseases  e.g.  scarlet  fever, 
diphtheria  and  typhoid  fever,  may  be  conveyed  by  milk. 

The  common  methods  of  adulterating  milk,  namely, 
by  abstracting  fat  or  adding  water,  diminish  the  food 
value  but  there  has  been  great  exaggeration  of  the  im- 
portance of  these  changes.  It  can  scarcely  be  sound 
to  declare,  as  has  occasionally  been  done  by  those  en- 
gaged in  promoting  sanitary  legislation,  that  milk  re- 
duced in  fat  by  legitimate  processes  or  even  watered  to 
a  considerable  extent  is  unwholesome.  It  is  occasion- 
ally stated  that  the  digestion  of  the  proteids  of  milk  is 
dependent  on  the  presence  of  a  certain  amount  of  fat, 
but  the  experimental  or  clinical  evidence  of  this  is  ap- 
parently not  precise.  Se'veral  competent  authorities, 
e.  g.,  Vieth,  Uffelmann  and  Hartshorne,  have  unhesita- 
tingly declared  even  closely  skimmed  milk  to  be 
wholesome.  As  regards  watered  milk,  it  would  be  pre- 


56  DATA    FOR    MILK    INSPECTION. 

posterous  to  assert  that  an  article  which  is  wholesome 
when  containing  nine  per  cent,  of  non-fatty  solids,  be- 
comes unwholesome  when  containing  eight  per  cent. 

The  unwholesomeness  of  milk  arises  not  from  change 
in  the  proportions  of  its  principal  ingredients,  but  from 
contamination  with  microorganisms.  The  danger  from 
certain  specific  organisms  has  been  mentioned,  but 
the  more  frequent  danger  is  from  the  ordinary  non-pa- 
thogenic or  putrefactive  microbes,  which,  unless  special 
care  be  taken,  are  invaribly  present  and  multiply  rapid- 
ly. To  prevent  such  conditions,  resort  is  had  to 
sterilization  by  heat.  Brief  exposure  to  a  temperature 
of  2 1 2°  F  is  sufficient  in  most  cases,  but  if  the  milk  be 
subsequently  exposed  to  air  at  ordinary  temperatures, 
or  mixed  with  unboiled  water,  it  will  be  again  contam- 
inated and  undergo  putrefactive  changes.  In  the  warm- 
er seasons  of  the  year,  these  changes  occur  with  great 
rapidity.  Since  clinical  experience  seems  to  show  that 
boiled  milk  is  frequently  an  unsatisfactory  food  for  in- 
fants, methods  of  fractional  sterilization  at  lower  tem- 
peratures have  been  suggested.  These  depend  on 
the  fact,  that,  while  spores  and  immature  microbes 
require  a  rather  high  temperature  for  their  destruc- 
tion, fully  developed  organisms  are  more  easily  kill- 
ed. By  heating  the  milk,  therefore,  to  a  temperature 
much  below  the  boiling  point,  the  adult  microbes  are 
killed,  while  the  milk  solids 'are  not  unfavorably  affect- 
ed. The  spores  and  immature  organisms  will,  however, 
survive  and  may  in  a  few  hours  develop,  hence  the 
milk  is  again  heated,  as  before,  and  these  later  devep- 


ABNORMAL   MILKS.  57 

oped  organisms  will  be  killed.  This  process  is  repeat- 
ed several  times  and  finally  complete  sterilization  is  ef- 
fected. 

For  the  practical  purpose  of  rendering  milk  safe  as 
an  article  of  food,  it  is  not  necessary  to  make  repeated 
heatings.  Numerous  investigations  are  reported  on 
this  point,  one  of  the  most  recent  being  a  paper  by 
Dr.  R.  G.  Freeman  (Med.  Rec.  June  10,1893).  A 
temperature  of  i6;°F  (75°C)  continued  for  fifteen  min- 
utes, followed  by  rapid  cooling  by  immersing  the  con- 
taining vessel  in  water,  will  kill  the  adult  forms  of  most 
microbes,  and  milk  so  treated  will  remain  unaltered  for 
one  or  two  days  and  will  not  have  suffered  any  ap- 
preciable loss  of  digestibility,  even  for  infants. 

When  it  is  considered  that  milk  is  almost  the  only 
form  of  animal  food  that  is  eaten  in  the  uncooked 
condition,  by  civilized  communities,  the  importance  of 
the  facts  above  noted  will  be  apparent.  Some  inter- 
esting data  as  to  the  association  of  consumption,  diph- 
theria, and  similar  diseases,  with  the  maintenance  of 
dairies  have  been  collected,  but  the  discussion  of  this 
feature  of  the  question  would  be  out  of  place  here. 
Enough  is  known  to  show  that  raw  milk  is  not  a  safe 
article  of  food,  unless  collected  with  such  precautions 
as  will  prevent  the  introduction  of  infectious  matter. 

Artificial  coloring  matters  do  not  involve  any 
serious  danger  to  health,  except  Martius'  yellow, 
(dinitroalpnanaphthol)  which  is  poisonous.  The  obvi- 
ous objection  to  their  use  is  that  they  enable  milk  of 
inferior  quality  to  be  substituted  for  rich  milk.  It  is 

E 


58  DATA  FOR  MILK  INSPECTION. 

worthy  of  note  that  the  assertion,  occasionally  made, 
that  urine  is  employed  in  the  preparation  of  annatto,  is 
of  little  weight,  since  the  annatto  sold  for  diary  use  is 
prepared  by  unobjectionable  methods. 

Abnormal  milks. — Milk  occasionally  becomes  blue 
on  the  surface,  the  color  forming  in  patches  in  propor- 
tion as  the  cream  rises.  The  condition  is  due  to  the 
development  of  a  chromogenic  bacillus,  first  noted  by 
Ehrenberg,  and  by  him  called  Vibrio  syncyanus,  but 
now  more  correctly  called  Bacillus  syncyanus.  The 
condition  sometimes  prevails  in  epidemic  form.  The 
butter  prepared  from  such  milk  possesses  a  greenish 
color  and  a  disagreeable  butyric  odor.  The  bacillus 
seems  to  be  non-pathogenic.  Hueppe  fed  animals  on 
food  mixed  with  strong  cultures  of  it,  and  observed  no 
serious  results.  To  prevent  the  development  and 
spread  of  the  bacillus  it  is  recommended  that  the  ves- 
sels intended  to  receive  the  milk  be  washed  with  boil- 
ing water.  Reiset  states  that  blue  milk  may  be  used  for 
the  production  of  butter  by  adding  0.5  gram  of  acetic 
acid  to  each  liter  (8  grains  to  the  quart). 

Red  milk  is  due  to  accidental  contamination  with 
the  Bacillus  prodigiosus.  The  spores  of  this  microbe 
exist  in  the  atmosphere  and  rapidly  develop  when 
they  fall  upon  any  nutritive  medium.  The  microbe 
does  not  appear  to  have  any  pathogenic  properties. 

Ropy  milk. — This  condition  is  occasionally  seen 
during  moist  warm  weather.  The  milk  when  drawn  may 


ABNORMAL  MILKS.  59 

not  show  any  unusual  properties,  but  in  a  few  hours 
becomes  so  viscid  that  a  spoonful  of  it  may  be  lifted 
several  inches  without  breaking  the  connection  be- 
tween the  two  portions.  The  nature  and  cause  of  the 
change  are  not  known.  The  phenomenon  generally 
appears  rather  suddenly  and  does  not  last  long,  almost 
always  disappearing  promptly  on  the  advent  of  colder 
weather.  Cases  are  known  in  which  the  milk  thus  af- 
fected has  been  used  as  food  without  any  apparent 
unfavorable  effect. 


MILK   PRODUCTS. 

CONDENSED  MILK. 

A  few  brands  of  condensed  milk  in  the  market 
under  the  name  of  "evaporated  cream,"  consist  merely 
of  whole  milk  concentrated  to  about  two-fifths  of  its 
bulk,  but  most  condensed  milks  contain  a  considerable 
amount  of  cane  sugar.  These  samples  represent,  usual- 
ly, whole  milk  concentrated  to  about  one-third  or  two- 
sevenths  of  its  original  volume.  On  account  of  the 
presence  of  cane  sugar,  the  fat  is  preferably  estimated 
by  the  Adams'  process,  and  for  the  same  reason,  in 
the  determination  of  the  total  solids,  the  sample  should 
be  well  spread  in  a  thin  layer  to  facilitate  drying.  The 
use  of  ignited  asbestos  in  a  platinum  dish  is  to  be  re- 
commended (see  page  18). 

Cane  and  milk  sugars. — About  30  grams  of  the 
sample  are  accurately  weighed,  placed  in  a  100  c.  c. 
flask,  diluted  to  80  c.  c.  and  heated  to  boiling.  The 
heating  is  necessary  to  avoid  birotation,  since  con- 
densed milk  often  contains  crystallized  milk  sugar. 
The  solution  is  cooled,  1.5  c.  c.  of  acid  mercuric  ni- 
trate solution  (p.  37)  added,  the  liquid  made  up  to  100 
c.  c.,  well  shaken,  filtered  through  a  dry  filter  and  the 
polarimetric  reading  taken  at  once.  It  will  be  the  sum 
of  the  effects  of  the  two  sugars.  The  volume  of  the 

60 


CONDENSED  MILK.  61 

sugar-containing  liquid  is  calculated  by  allowing  for 
the  precipitated  proteids  and  fat,  as  described  under 
the  determination  of  milk  sugar. 

50  c.  c.  of  the  filtrate  are  placed  in  a  flask  marked 
at  55  c.  c.,  a  piece  of  litmus  paper  dropped  in  and  the 
excess  of  nitric  acid  cautiously  neutralized  by  sodium 
hydroxid  solution.  The  liquid  is  then  faintly  acidified 
by  a  single  drop  of  acetic  acid,  (it  must  not  be  alkaline) 
a  few  drops  of  an  alcoholic  solution  of  thymol  added, 
and  then  2  c.  c.  of  a  solution  of  invertase,  prepared 
by  grinding  half  a  cake  of  ordinary  compressed  yeast 
with  10  c.  c.  of  water  and  filtering.  The  flask  is 
corked  and  allowed  to  remain  at  a  temperature  of 
100°  to  iio°F.  for  24  hours.  The  cane  sugar  will  be 
inverted  while  the  milk  sugar  will  be  unaffected.  The 
flask  is  filled  to  the  mark  (55  c.  c.)  with  washed 
aluminum  hydroxid  and  water,  mixed,  filtered  and  the 
polarimetric  reading  taken. 

The  rototary  powers  of  cane  sugar  and  dextrose 
are  not  appreciably  affected  by  temperature  within 
the  limits  of  ordinary  experiments.  The  same  may 
be  said  of  milk  sugar  (see  page  40).  Invert  sugar,  by 
reason  of  the  levulose  present,  is  materially  affected 
by  the  temperature.  Thus,  a  solution  of  cane  sugar, 
which,  before  inversion,  causes  a  rotation  of  -f  100  an- 
gular degrees,  has  after  inversion,  if  observed  at  32°F., 
a  rotation  of  — 44  degrees,  a  total  change  of  144;  but 
at7O°F.  the  reading  will  be  only — 33  angular  degrees, 


62  MILK   PRODUCTS. 

a  total  change  of  133.  The  following  formula  is  to  be 
used  for  calculation. 

IPO  D 
C=  144-  (/-  32) 

3-6 

in  which  C  equals  the  angular  rotation  due  to  the 
uninverted  cane  sugar,  D  the  difference  in  the  polari- 
metric  reading  before  and  after  inversion,  and  t  the 
temperature  in  Fahrenheit  degrees.  Since,  in  the 
performance  of  the  inversion,  the  liquid  has  been  di- 
luted from  50  to  55  c.  c.,  the  polarimetric  reading 
must  be  increased  in  proportion,  before  the  value  of 
D  is  found.  The  value  of  C  found  by  the  equation, 
deducted  from  the  reading  before  inversion,  will  give 
the  angular  rotation  due  to  the  milk  sugar. 

The  specific  rotatory  power   of   cane  sugar   varies 
slightly   with   the  concentration.     Tollens  gives    the 
following  formula,  in  which  5  is  the  sepecific  rotatory 
power  and  £7  the  concentration  in  grams  per  100  c.  c. 
5  ==  66.386  +  .015035  C  —  .0003986  C* 

A  method  which  has  given  good  results  in  our 
hands,  is  to  take  the  reading  for  milk  and  cane  sugars 
as  described  above  and  determine,  in  another  portion 
of  the  sample,  the  milk  sugar  by  Fehling's  solution, 
which  is  not  reduced  by  cane  sugar.  About  three 
grams  of  the  condensed  milk  (corresponding  to  about 
ten  grams  of  ordinary  milk)  are  accurately  weighed, 
diluted  with  water,  treated  with  copper  sulfate  and 
sodium  hydroxid  as  described  under  the  determination 


BUTTER.  63 

of  proteids  by  the  Ritthausen  method,  the  liquid  made 
up  to  200  c.  c.,  mixed,  filtered  through  a  dry  filter  and 
the  reducing  power  of  100  c.  c.  of  the  filtrate  deter- 
mined by  Soxhlet's  method  as  described. 


BUTTER. 

Butter,  commercially,  consists  of  a  variable  mixture 
of  fat,  water  and  curd,  obtained  by  churning  cream 
from  cow's  milk.  The  water  contains  in  solution  milk 
sugar  and  the  salts  of  the  milk.  Common  salt  is 
usually  present,  being  added  after  the  churning.  Arti- 
ficial coloring  is  frequently  used. 

The  composition  of  commercial  butter  usually  varies 
within  the  following  limits: — 

Fat     ....  78  per  cent,  to  94  per  cent. 

Curd  ....  i     "  "      "     3     "      '< 

Water     ...  5     "  "      "   14     "      « 

Salt    ....  o     "  "      "     7     «      " 

Nostrums  for  butter  making. — Preparations  pur- 
porting to  have  the  power  to  increase  the  yield  of 
butter  from  a  given  weight  .of  milk  are  now  sold. 
One  of  these,  advertised  under  the  name  "  black  pep- 
sin," has  been  found  to  contain  salt ,  annatto  and  a  small 
amount  of  rennet.  Pepsin  has  also  been  used.  These 
curdle  the  milk  and  allow  the  incorporation  of  much 
cheese  and  water  with  the  butter.  It  has  been  found 
that  butter  may  also,  without  the  addition  of  any  chem- 
icals, be  incorporated  with  a  large  amount  of  cream. 


64  MILK  PRODUCTS. 

Butter  containing  over  forty  per  cent,  of  water,  has  been 
sold  in  this  city.  Such  samples  are  pale  and  spongy, 
lose  weight  and  become  rancid  very  rapidly. 

It  is  generally  considered  that  butter  should  not  con- 
tain more  than  1 6  per  cent,  water.  An  excess  of  water 
diminishes  the  keeping  quality. 

The  following  methods  for  the  analysis  of  butter 
have  been  adopted  by  the  Association  of  Official  Ag- 
ricultural Chemists: — 

"Sampling. — If  large  quantities  of  butter  are  to  be 
sampled,  a  butter  trier  or  sampler  may  be  used.  The 
portions  drawn,  about  500  grams,  are  to  be  carefully 
melted  in  a  closed  vessel,  at  as  low  a  heat  as  possible, 
and  when  melted  the  whole  is  to  be  shaken  violently 
for  some  minutes  till  homogeneous.  The  mass  must  be 
sufficiently  solidified  to  prevent  the  separation  of  the 
water  and  fat.  A  portion  is  then  placed  in  the  vessel 
from  which  it  is  to  be  weighed  for  analysis,  and  should 
nearly  or  quite  fill  it.  It  should  be  kept  in  a  cold  place 
until  analyzed.  Determinations  are  made  as  follows : — 

Water. — 1.5-2.5  grams  are  dried  to  constant  weight 
at  the  temperature  of  boiling  water  in  a  dish  with  a  flat 
bottom,  having  a  surface  of  at  least  20  sq.  cm. 

Fat. — The  dry  butter  from  the  water  determination 
is  dissolved  in  the  dish  with  absolute  ether,  or  with  76° 
benzin.  The  contents  ol  the  dish  are  then  transferred 
to  a  Gooch  crucible  with  the  aid  of  a  wash-bottle  filled 
with  the  solvent,  and  are  washed  until  free  from  fat. 
The  crucible  and  contents  are  dried  at  the  temperature 


BUTTER.  65 

of  boiling  water,  until  the  weight  is  constant. 

Casein  and  Ash. — The  crucible  containing  the  res- 
idue from  the  fat  determination,  consisting  of  the  casein 
and  salts,  is  covered  and  heated,  gently  at  first,  and 
gradually  raising  the  temperature  to  just  below  red- 
ness. The  cover  may  then  be  removed  and  the  heat 
continued  till  the  contents  of  the  crucible  are  white. 
The  loss  in  weight  of  the.  crucible  and  contents  repre- 
sents the  weight  of  the  casein,  and  the  residue  in  the 
crucible,  ash.  /; 

A  weighed  paper  filter  may  replace  the  Gooch 
crucible. 

Antiseptic  substances  in  milk  may  find  their 
way  into  the  butter  made  from  it.  They  will  be  dis- 
solved in  the  water,  and  may  be  detected  by  separat- 
ing this,  by  melting,  and  testing  it  as  directed  under 
milk. 

Oleomargarin. — Under  this  term  is  now  included 
by  act  of  Congress,  any  oleaginous  substance,  intended 
as  a  substitute  for  butter,  containing  any  proportion  of 
fat  other  than  butter-fat.  The  term  "  margarine  "  is 
employed  in  England,  under  authority  of  an  act  of 
Parliament,  with  the  same  significance.  The  principal 
materials  employed  in  the  preparation  of  butter-sub- 
stitutes are  cottonseed  oil,  mutton  fat  and  beef  fat.  As 
usually  manufactured,  they  are  wholesome  and  econ- 
omical. 

Butter  fat,  like  most  fats,  consists  of  a  mixture  of  the 
ethers  of  tritenyl  (C3  H5  )  but  is  peculiar  among  animal 


66  MILK    PRODUCTS. 

fats  in  containing  notable  proportions  of  acid  radicles 
with  a  small  number  of  carbon  atoms.  The  exact  ar- 
rangement is  not  known,  but  the  weight  of  opinion  is 
that  it  is  not  a  mixture  of  simple  fats,  but  that  several 
acid  radicles  are  united  to  the  same  tritenyl  molecule. 
When  saponified  by  sodium  hydroxid  and  treated 
with  acid,  the  individual  fatty  acids  are  obtained.  It 
is  upon  the  recognition  of  the  peculiar  acid  radicles 
that  the  most  satisfactory  method  of  distinguishing 
butter  from  other  fats  is  based.  Since  the  relative  pro- 
portion of  these  radicles  differs  in  different  samples,  the 
quantitive  estimation  cannot  be  made  with  accuracy, 
but  when  the  foreign  fats  are  substituted  to  the  extent 
of  25  per  cent,  or  more,  the  adulteration  can  be  detect- 
ed with  certainty  and  the  quantitive  determination  ap- 
proximately made. 

The  fatty  acids  containing  a  small  number  of  carbon 
atoms,  set  free  by  the  process  of  saponification  and 
treatment  with  acid  as  noted  above,  are  soluble  in  wa- 
ter and  volatile.  A  method  for  their  estimation  depend- 
ing on  their  solubilty  in  water  was  perfected  by 
Hehner,  but  has  now  been  displaced  by  a  distillation 
method  originally  suggested  by  Hehner  &  Angell,  but 
improved  by  Reichert  and  the  details  perfected  by 
others,  especially  Wollny,  and  now  generally  known 
as  the  Reichert-Wollny  method. 

We  have  modified  the  process  by  substituting  a  so- 
lution of  sodium  hydroxid  in  glycerol  as  the  saponify- 
ing agent,  by  which  the  time  required  is  much  shorten- 
ed, the  result  subject  to  less  variation,  and  the  titration 


BUTTER.  67 

more  exact.     The  following  reagents  are  required. 

Glycerol  Soda. — -100  grams  of  pure  sodium  hydrox- 
id  are  dissolved  in  100  c.  c.  of  distilled  water,  and  al- 
lowed to  stand  until  clear.  20  c.  c.  of  this  solution  are 
mixed  with  180  c.  c.  of  pure  concentrated  glycerol. 
The  mixture  may  be  conveniently  kept  in  a  capped  bot- 
tle holding  a  10  c.  c.  pipette. 

Sulfuric  Acid. — 20  c.  c.  of  pure  concentrated  sulfuric 
acid,  made  up  with  distilled  water  to  100  c.  c. 

Barium  Hydroxid. — An  approximately  decinormal, 
accurately  standardized,  solution  of  barium  hydroxid. 

Indicator. — An  alcoholic  solution  of  phenolphtha- 
lein. 

About  50  grams  of  the  sample  are  placed  in  a 
beaker,  and  heated  to  a  temperature  of  120°  to  I49°F,. 
until  the  water  and  curd  have  settled  to  the  bottom. 
The  clear  fat  is  then  poured  on  a  warm  dry  plaited  fil- 
ter, and  kept  in  a  warm  place  until  25  or  30  c.  c.  have 
been  collected.  If  the  filtrate  is  not  perfectly  clear,  it 
should  be  reheated  for  a  short  time  and  again  filtered. 

A  300  c.  c.  flask  is  washed  thoroughly,  rinsed  with 
alcohol  and  then  with  ether,  and  thoroughly  dried  by 
heating  in  the  water  oven.  After  cooling,  it  is  allowed 
to  stand  for  about  15  minutes  and  weighed.  A  pipette, 
graduated  to  5.75  c.  c.,  is  heated  to  about  I4O°F  and 
filled  to  the  mark  with  the  well  mixed  fat,  which  is 
then  run  into  the  flask.  After  standing  for  about  fif- 
teen minutes,  the  flask  and  contents  are  weighed.  20  c.c. 
of  the  glycerol  soda  are  added  and  the  flask  heated 
over  the  Bunsen  burner.  The  mixture  may  foam 


68 


MILK    PRODUCTS. 


somewhat;  this  may  be  controlled,  and  the  operation 
hastened,  by  shaking  the  flask.  When  all  the  water 
has  been  driven  off,  the  liquid  will  cease  to  boil,  and  if 
the  heat  and  agitation  be  continued  for  a  few  moments, 
complete  saponification  will  be  effected,  the  mixture 
becoming  perfectly  clear.  The  whole  operation,  exclu- 
sive of  weighing  the  fat,  requires  less  than  five  min- 
utes. The  flask  is  than  withdrawn  from  the  heat  and 
the  soap  dissolved  in  1 35  c.  c.  of  water.  The  first  por- 


tions of  water  should  be  added  drop  by  drop,  and  the 
flask  shaken  between  each  addition,  in  order  to  avoid 
foaming.  When  the  soap  is  dissolved,  5  c.  c.  of  the 
dilute  sulfuric  acid  are  added,  a  piece  of  pumice  drop- 
ped in  and  the  liquid  distilled  until  1 10  c.  c.  have  been 
collected.  The  condensing  tube  should  be  of  glass, 


BUTTER.  69 

and  the  distillation  conducted  at  such  a  rate  that  the 
above  amount  of  distillate  is  collected  in  30  minutes. 

The  distillate  is  usually  clear;  if  not,  it  should  be 
thoroughly  mixed,  filtered  through  a  dry  filter,  and 
100  c.  c.  of  the  filtrate  taken.  To  the  distillate,  about 
0.5  c.  c.  of  the  phenolphthalein  solution  are  added,  and 
the  standard  barium  hydroxid  run  in  from  a  burette 
until  a  red  color  is  produced.  If  only  100  c.  c.  of  the 
distillate  have  been  used  for  the  titration,  the  number 
of  c.  c.  of  barium  hydroxid  should  be  increased  by  one- 
tenth. 

When  it  is  intended  merely  to  distinguish  pure  but- 
ter and  pure  oleomargarin  it  will  be  sufficient  to  meas- 
ure into  the  flask  three  or  six  c.  c.  of  the  clear  fat, 
and  operate  upon  this  directly. 

A  blank  experiment  should  be  made  to  determine 
the  amount  of  decinormal  alkali  required  by  the  ma- 
terials employed.  With  a  good  quality  of  glycerol, 
this  will  not  usually  exceed  0.5  c.  c. 

Butter  (5  grams)  yields  a  distillate  requiring  from 
24  to  34  c.  c.  of  decinormal  alkali.  Several  instances 
have  been  published  in  which  genuine  butter  has  given 
a  figure  as  low  as  22.5  c.  c.,  but  such  results  are  un- 
common. The  materials  employed  in  the  preparation 
of  oleomargarin  yield  a  distillate  requiring  less  than 
l  c.  c.  of  alkali.  Commercial  oleomargarin  is  usually 
churned  with  milk  in  order  to  secure  a  butter  flavor, 
and  thus  acquiring  a  small  amount  of  butter-fat  yields 
distillates  capable  of  neutralising  from  I  to  2  c.  c.  of  al- 
kali. 


70  MILK    PRODUCTS. 

The  method  of  determining  the  volatile  acids  of  but- 
ter-fat, adopted  by  the  Association  of  Official  Agricul- 
tural Chemists,  is  as  follows  :— 

Caustic  soda  solution.  — 100  grams  of  sodium  hydrox- 
id  are  dissolved  in  100  c.  c.  of  pure  water.  It  should 
be  as  free  as  possible  from  carbonates,  and  be  pre- 
served from  contact  with  the  air. 

Alcohol,  of  about  95  per  cent.,  redistilled  with  caustic 
soda. 

Acid. — Solution  of  sulfuric  acid  containing  25  c.  c.  of 
strongest  acid  in  IOOO  c.  c.  of  water. 

Barium  hydroxid. — An  accurately  standardized,  ap- 
proximately decinormal  solution  of  barium  hydroxid. 

Indicator. — Alcoholic  solution  of  phenolphthalein. 

Saponification  flasks,  250  to  300  c.  c.  capacity,  of  hard 
well  annealed  glass,  capable  of  resisting  the  tension  of 
-alcohol  vapor  at  2I2°F. 

A  pipette,  graduated  to  deliver  40  c.  c. 

Distilling  apparatus. 

Burette. — A  accurately  calibrated  burette,  reading 
to  tenths  of  a  c.  c. 

Weighing  the  fat- — The  butter  or  fat  to  be  examined 
should  be  melted,  and  kept  in  a  dry  warm  place  at 
about  I45°F  for  two  or  three  hours,  until  the  moisture 
.and  curd  have  entirely  settled  out.  The  clear  super- 
natant fat  is  poured  off  and  filtered  through  dry  fil- 
ter paper  in  a  jacketed  funnel  containing  boiling  water. 
Should  the  filtered  fat  in  a  fused  state  not  be  perfectly 
clear,  the  treatment  above  mentioned  must  be  repeated. 

The   saponification    flasks   are   prepared  by  having 


BUTTER.  71 

them  throughly  washed  with  water,  alcohol  and  ether, 
wiped  perfectly  dry  on  the  outside,  and  heated  for  one 
hour  to  boiling  temperature.  The  flasks  should  then 
be  placed  in  a  tray  by  the  side  of  the  balance  and  cov- 
ered with  a  silk  handkerchief  until  they  are  perfectly 
cool.  They  must  not  be  wiped  with  a  silk  handker- 
chief within  fifteen  or  twenty  minutes  of  the  time  they 
are  weighed.  The  weight  of  the  flasks  having  been 
accurately  determined,  they  are  charged  with  the  melt- 
ed fat  in  the  following  way: 

A  pipette  with  a  long  stem,  marked  to  deliver  5.75 
c.  c.  is  warmed  to  a  temperature  of  about  1 3<D°F.  The 
fat  having  been  poured  back  and  forth  once  or  twice 
into  a  dry  beaker  in  order  to  throughly  mix  it,  is  taken 
up  in  the  pipette  and  the  nozzle  of  the  pipette  carried 
to  near  the  bottom  of  the  flask,  having  been  previously 
wiped  to  remove  any  adhering  fat,  and  5.75  c.  c.  of  fat 
are  allowed  to  flow  into  the  flask.  After  the  flasks 
have  been  charged  in  this  way,  they  should  be  recover- 
ed with  the  silk  handkerchief  and  allowed  to  stand 
fifteen  or  twenty  minutes,  when  they  are  again  weighed. 

The  saponification. — Ten  c.  c.  of  95  per  cent,  alcohol 
are  added  to  the  fat  in  the  flask,  and  then  2  c.  c.  of  the 
concentrated  soda  solution;  a  soft  cork  stopper  is  now 
inserted  in  the  flask  and  tied  down  with  a  piece  of 
twine.  The  saponification  is  then  completed  by-  plac- 
ing the  flask  upon  the  water  or  steam  bath.  The  flask 
during  the  saponification,  which  should  last  one  hour, 
should  be  gently  rotated  from  time  to  time,  being 
careful  not  to  project  the  soap  for  any  distance  up  its 


72  MILK    PRODUCTS. 

sides.  At  the  end  of  an  hour  the  flask,  after  having 
been  cooled  to  near  the  room  temperature,  is  opened. 

Removal  of  the  alcohol. — The  stoppers  having  been 
laid  loosely  in  the  mouth  of  the  flask,  the  alcohol  is  re- 
moved by  dipping  -the  flask  into  a  steam  bath.  The 
steam  should  cover  the  whole  of  the  flask  except  the 
neck.  After  the  alcohol  is  nearly  removed,  frothing 
may  be  noticed  in  the  soap,  and  to  avoid  any  loss  from 
this  cause  or  any  creeping  ot  the  soap  up  the  sides  of 
the  flask,  it  should  be  removed  from  the  bath  and 
shaken  to  and  fro  until  the  frothing  disappears.  The 
last  traces  of  alcohol  vapor  may  be  removed  from  the 
flask  by  waving  it  briskly,  mouth  down,  to  and  fro. 

Dissolving  the  soap. — After  the  removal  of  the  alco- 
hol the  soap  should  be  dissolved  by  adding  100  c.  c.  of 
recently  boiled  distilled  water,  warming  on  the  ste,am 
bath  with  occasional  shaking,  until  solution  of  the  soap 
is  complete. 

Setting  free  the  fatty  acids. — When  the  soap  solution 
has  cooled  to  about  I45°F  the  fatty  acids  are  separat- 
ed by  adding  40  c.  c.  of  the  dilute  sulphuric  acid  so- 
lution mentioned  above. 

Melting  the  fatty  acid  emulsion. — The  flask  should 
now  be  re-stoppered  as  in  the  first  instance,  and  the 
fatty  acid  emulsion  melted  by  replacing  the  flask  on 
the  steam  bath.  According  to  the  nature  of  the  fat  ex- 
amined, the  time  required  for  the  fusion  of  the  fatty 
acid  emulsions  may  vary  from  a  few  minutes  to  several 
hours. 


BUTTER.  73 

The  distillation. — After  the  fatty  acids  are  complete- 
ly melted,  which  can  be  determined  by  their  forming  a 
transparent  oily  layer  on  the  surface  of  the  water,  the 
flask  is  cooled  to  room  temperature,  and  a  few  pieces 
of  pumice  stone  added.  The  pumice  stone  is  prepared 
by  throwing  it,  at  a  white  heat,  into  distilled  water, 
and  keeping  it  under  water  until  used.  The  flask  is 
now  connected  with  a  glass  condenser,  slowly  heated 
with  a  naked  flame  until  ebullition  begins,  and  then 
the  distillation  continued  by  regulating  the  flame  in 
such  a  way  as  to  collect  1 10  c.  c.  of  the  distillate  in,  as 
nearly  as  possible,  thirty  minutes.  The  distillate 
should  be  received  in  a  flask  accurately  graduated  at 
no  c.  c. 

Titration  of  the  volatile  acids. — The  1 10  c.  c.  of  dis- 
tillate, after  thorough  mixing,  are  filtered  through 
dry  filter  paper  and  collected  in  a  flask  marked 
at  100  c.  c.  100  c.  c.  of  the  filtered  distillate  are 
poured  into  a  beaker  holding  from  200  to  250  c.  c., 
0.5  c.  c  of  phenolphthalein  solution  added,  and  decinor- 
mal  barium  hydroxid  run  in  until  a  red  color  is  produced. 
The  contents  of  the  beaker  are  then  returned  to  the 
measuring  flask  to  remove  any  acid  remaining  therein, 
poured  again  into  the  beaker,  and  the  titration  contin- 
ued until  the  red  color  produced  remains  apparently 
unchanged  for  two  or  three  minutes.  The  number  of 
cubic  centimeters  of  decinormal  barium  hydroxid  re- 
quired should  be  increased  by  one-tenth. 

Many  other  methods  of  detecting  butter  adultera- 
tion have  been  proposed.  The  specific  gravity  of  the 


74  MILK  PRODUCTS. 

melted  fat  is  of  value  in  this  connection,  but  the  dis- 
tinction between  butter  and  its  substitutes  is  not  so 
sharp  as  with  the  distillation  method.  The  same  re- 
mark applies  to  the  iodin  absorption  figure  and  to  the 
refractive  index.  The  latter  can  be  accurately  meas- 
ured by  means  of  an  instrument  called  the  oleo-refrac- 
tometer. 

Considerable  use  has  been  made  of  a  method  based 
upon  the  detection  of  crystalline  structure  by  examin- 
ation with  polarized  light.  Such  condition  indicates 
however,  merely  that  the  sample  has  been  previously 
melted.  By  churning  oleo-oil  with  cream,  a  material 
is  obtained  which  shows  no  crystalline  structure  when 
examined  in  this  way. 

Commercial  forms  of  oleomargarin  and  butter  exhibit 
characteristic  differences  on  heating,  which  may  be 
utilized  for  rapidly  sorting  a  collection  of  samples. 
When  butter  is  heated  in  a  small  tin  dish  directly 
over  a  gas  flame,  it  melts  quietly,  foams  and  may  run 
over  the  dish.  Oleomargarin,  under  the  same  condi- 
tions, sputters  noisily  as  soon  as  heated  and  foams  but 
little.  Even  mixtures  of  butter  and  other  fats  show 
this  sputtering  action  to  a  considerable  extent.  The 
effect  depends  upon  the  condition  in  which  the  ad- 
mixed water  exists,  and  the  test  is  not  applicable  to 
butter  which  has  been  melted  and  reworked. 

An  alcoholic  solution  of  sodium  hydroxid  heated 
for  a  moment  with  butter  and  then  emptied  into  cold 
water,  gives  a  distinct  odor  of  pineapples  (due  to  ethyl 


CHEESE.  75 

butyrate)  while  oleomargarin  gives  only  the  alcoholic 
odor. 

Butter-Colors. — The  following  coloring  matters 
are  stated  to  have  been  found  in  butter  :  carrot  color, 
annatto,  marigold  and  carthamus  flowers,  turmeric  and 
certain  coal-tar  colors. 

The  following  test,  described  by  E.  W.  Martin,  we 
have  found  very  satisfactory.  Dissolve  2  parts  of 
carbon  disulfid  in  15  parts  of  alcohol,  by  adding  small 
portions  of  the  disulfid  to  the  alcohol  and  shaking 
gently ;  25  c.  c.  of  this  mixture  are  placed  in  a  con- 
venient tube,  5  grams  of  the  butter-fat  added,  and 
the  tube  shaken.  The  disulfid  falls  to  the  bottom  of 
the  tube,  carrying  with  it  the  fatty  matter,  while 
any  artificial  coloring  matter  remains  in  the  alcohol. 
The  separation  takes  place  in  from  one  to  three  min- 
utes. If  the  amount  of  the  coloring  matter  is  small 
more  of  the  fat  may  be  used. 

CHEESE. 

Cheese  is  obtained  by  the  action  of  rennet,  which 
is  usually  derived  from  the  fourth  stomach  of  the  calf. 
The  action  is  due  to  a  non-organized  ferment  (enzyme) 
rennin,  which  acts  directly  on  the  proteids,  and  does 
not  produce  its  effect  through  the  intervention  of 
acid.  The  curd  (cheese)  undergoes,  by  keeping,  va- 
rious decompositions,  some  essentially  putrefactive, 
and  undoubtedly  due  to  the  action  of  microbes. 
These  changes,  known  as  ripening,  do  not  take  place 


76  MILK    PRODUCTS. 

in  a  satisfactory  manner  when  the  curd  is  produced  by 
the  action  of  acids  or  neutral  mineral  salts,  possibly 
because  these  agents  interfere  with  the  action  of  the 
microbes  and  enzymes  on  which  the  ripening  depends. 
Skimmed  milk  is  not  infrequently  used  for  the  pro- 
duction of  cheese,  and  foreign  fats  such  as  are  used 
in  the  manufacture  of  oleomargarin  are  sometimes 
incorporated. 

The  analytical  points  to  be  determined  in  regard  to 
cheese,  are  amounts  of  water,  fat,  casein,  ash,  the 
presence  of  fats  other  than  butter-fat  and  coloring  mat- 
ters. 

Care  should  be  taken  to  select  for  analysis  a  sample 
which  represents  the  average  composition  of  the  en- 
tire cheese.  A  thin  section,  reaching  to  the  centre,  is 
preferable,  and  portions  from  various  parts  of  this 
should  be  cut  fine  and  mixed.  This  should  be  done 
with  as  little  exposure  to  air  as  possible,  to  avoid  loss 
of  water. 

The  following  methods  for  water,  fat,  ash  and  casein 
are  those  provisionally  adopted  by  the  Association  of 
Official  Agricultural  Chemists. 

Water. — From  5  to  10  grams  of  cheese  should  be 
taken,  and  placed  in  thin  slices  in  a  weighed  plat- 
inum or  porcelain  dish  which  contains  a  small  quantity 
of  freshly  ignited  asbestos,  to  absorb  the  fat  which 
may  run  out  of  the  cheese.  The  mass  is  then  heated 
in  a  water  oven  for  ten  hours,  and  weighed;  the  loss 
in  weight  is  to  be  considered  as  water. 

Ash. — The  dry  residue  from  the  water  determina- 


CHEESE.  77 

tion  may  be  taken  for  the  ash.  If  the  cheese  be  rich, 
the  asbestos  will  be  saturated  therewith.  This  mass 
may  be  ignited  carefully,  and  the  fat  allowed  to  burn 
off,  the  asbestos  acting  as  a  wick.  No  extra  heating 
should  be  applied  during  the  operation,  as  there  is 
danger  of  spurting.  When  the  flame  has  died  out,  the 
burning  may  be  completed  in  a  muffle  at  low  redness. 
When  desired,  the  salt  may  be  determined  in  the  ash 
by  titration  with  silver  nitrate  and  potassium  chromate. 

Fat. — 5  to  10  grams  of  the  sample  are  ground  in  a 
small  mortar  with  about  twice  the  weight  of  anhydrous 
copper  sulfate.  The  grinding  should  be  continued 
until  the  cheese  is.  finely  pulverized  and  evenly  dis- 
tributed throughout  the  mass,  which  will  have  a  uni- 
form blue  color.  This  mixture  is  transferred  to  a  glass 
tube  which  has  strong  filter  paper,  supported  by  a 
piece  of  muslin,  tied  over  the  end.  A  little  of  the 
clean  anhydrous  copper  sulfate  is  put  into  the  tube 
next  to  the  filter  before  introducing  the  mixture  con- 
taining the  cheese.  On  top  of  the  mixture  is  placed 
a  tuft  of  ignited  asbestos,  and  the  contents  of  the  tube 
extracted  with  anyhydrous  ether  in  the  continuous  ex- 
traction apparatus,  for  15  hours.  The  ether  is  re- 
moved as  usual  and  the  fat  dried  at  2I2°F.,  to  a  con- 
stant weight. 

This  fat  may  be  used  to  determine  the  presence  or  ab- 
sence of  oleomargarin,  by  applying  the  Reichert  test. 

Casein. — The  nitrogen  of  about  2  grams  of  the 
cheese  is  determined  by  the  Kjeldahl-Gunning  method. 


7  8  MILK    PRODUCTS. 

This  multiplied  by  6.38  gives  casein. 

The  fat  may  be  estimated  by  the  centrifugal  method, 
as  follows : — 

About  5  grams  of  the  mixed  cheese  are  weighed 
and  transferred  to  the  bottle,  the  last  portions  being 
washed  in  with  the  aid  of  water.  A  few  drops  of  am- 
monium hydroxid  are  added,  and  sufficient  water  to 
make  the  liquid  about  15  c.  c.  The  liquid  is  warmed 
with  occasional  shaking,  until  the  cheese  is  well  disin- 
tegrated, and  then  treated  as  a  sample  of  milk.  The 
percentage  of  fat  is  found  by  multiplying  the  percent- 
age reading  by  15.45  and  dividing  by  the  number  of 
grams  of  cheese  taken  for  analysis. 

Chrome  yellow  has  been  found  in  the  rind  of  cheese. 
It  may  be  detected  by  ashing  the  same  in  a  porcelain 
crucible,  assisting  the  burning  of  the  carbon  by  a 
little  nitric  acid,  and  applying  the  usual  tests  for  lead 
and  chromium. 

Cheese  contains  small  amounts  of  milk  sugar,  lactic 
and  other  organic  acids. 

ANALYSES  OF  VARIOUS  CHEESES. 

Proteids  Fat  Salts  Water 

Cheshire.  .  .  36.1  25.5  4.8  30.4 

Gruyere  .  .  .  35.1  28.0  4.8  32.0 

Roquefort  .  .  32.9  32.3  4.4  26.5 

Cheddar  .  .  28.4  31.1  4.5  56.0 

Camembert  .  .  18.9  21.0  4.7  51.9 

Skim  Milk  .  .  45.0  5.9  5.2  43.8 


APPENDIX. 


79 


80 


w 

TABLE  FOR  CORRECTING  THE  SPECIFIC  GRAVITY  OF 
MILK  ACCORDING  TO  TEMPERATURE. 

BY   DR.    P.    VIETH,    F.    C.    S.    &C. 


DIRECTIONS  FOR  USE. 

Find  the  Temperature  of  the  Milk  in  the  uppermost  horizontal 
line,  and  the  Specific  Gravity  in  the  first  vertical  column. 
In  the  same  line  with  the  latter,  under  the  Temperature,  is 
given  the  Corrected  Specific  Gravity. 

I  or  Example:  Supposing  the  Temperature  to  be  51°,  and  the 
Specific  Gravity,  34°,  the  Specific  Gravity  corrected  to  60° 
Farenheit,  is  32.9  ;  or  if  the  Temperature  is  66°,  and  the 
Specific  Gravity  29,  the  Corrected  Specific  Gravity  is  29.8 


COKFFCTIONS    FOR    TEMPERATURE. 


81 


IO2O 
21 
22 

23 
24 

25 
26 
27 

28 
29 
30 
31 
32 

33 
34 
35 


\                                       / 

46 

47 

48 

49 

50 

51 

52 

53 

54 

55 

19.0 

19.1    19.1    19.2 

19.2 

19-3 

19.4 

19.4 

J9-5 

19.6 

20.  o 

20.0 

20.1 

20.2 

20.2 

20.3 

20.3 

20.4 

20.5 

20.6 

21.  0 

21.0 

21.  I 

21.2 

21.2 

21.3 

21.3 

2E.4 

21.5    21.  6 

22.  0 

22.0 

22.1 

22.2     22  2 

22.3 

22-3J    22.4 

22.5 

22.6 

22.9 

23.0 

23.  1 

23.2     23.2     23.3 

23-3;    23.4 

23-5 

23-6 

23-9 

24.0    24.0    24  c    24.1    24.2 

24.3:    24.4 

24-5 

24.6 

j 

24.9 

24.9    25  o   25.1    25.1!  25.2 

25-2     25.3 

25-4 

25-5 

25-9 

25-9 

26.0     26.1     26.1     26.2 

26.2     26.3 

26.4    26.5 

268 

26.8 

26.9;  27.0    27.  o(  27.1 

27.2     27.3     27.4     27.5 

27.8 

27.8 

27.9     280     28.0     28.1 

23.2 

28.3!    28.4 

28.5 

28.7 

28.7 

| 

28.8!    28.9     29.0     29.1 

29.1 

29.2 

29.3!  29.4 

29.6 

29.6     29.7     29.8     29.9     30.0     30.1 

30.2     30.3!    30.4 

| 

30-5 

30.5     30.6     30.7     30.9     31.0 

3I-1 

31.2     31.31    31.4 

31-4 

31-4 

31-5 

31.6     3I.8i    31.9     32.0 

32.1     32.3 

32.4 

32.3 

32-3 

32.4 

32.5 

32.7     32.9 

33-0 

33-i    33-2 

33-3 

33-i    33-2    33-4 

33-5 

33-6     33-8 

1 

33-9 

34-0   34-2 

34-3 

82 


CORRECTIONS    FOR    TEMPERATURE. 


DEGREES  OF  THERMOMETER  (Fahrenheit] 


IO2O 
21 
22 

23 
24 

25 
26 

27 

28 

29 
30 
31 
32 

33 
34 
35 


56 

57 

58 

59 

60 

61 

62 

63 

64 

65 

19.7 

19.8 

19.9 

19.9 

2O.O 

20.1 

20.2 

20.2 

20.3 

20.4 

20.7 

20.8 

20.9 

20.9 

21.0 

21.  [ 

21.2 

21-3 

21.4 

2t-5 

21.7 

21.8 

21.9 

21.9 

22.0 

22.1 

22.2 

22.3 

22.4 

22.5 

22.7 

22.8 

22.8 

22.9 

230 

23.1 

23.2 

23-3 

23-4 

23-5 

23.6 

23-7 

23-8 

23-9 

24.0 

24.1 

24.2 

24-3 

24.4 

24.5 

24.6 

24.7 

24.8 

249 

25.0 

'5-1 

25.2 

25.3 

25-4 

25-5 

25.6 

25-7 

253 

25-9 

26.0 

26.1 

26.2 

26.3 

26.5 

26.6 

26.6 

26.7 

26.8 

26.9 

27.0 

27.1 

27-3 

27.4 

27.5 

27.6 

276 

27-7 

27.8 

27-9 

28.0 

28.1 

28.3 

28.4 

28.5 

28.6 

28.6 

28.7 

28.8 

289 

29.0 

29.1 

29-3 

29.4 

29-5 

29.6 

29.6 

29.7 

29.8 

29.9 

3<J.O 

30.1 

30-3 

30.4 

30.5 

30.7 

30-5 

30.6 

30.8 

30-9 

3i.o 

31.2 

51-3 

3L4 

3L5 

31-7 

31-5 

3i-6 

3J-7 

3J-9 

32.0 

32.2 

32.3 

32.5 

32.6 

32-7 

32.5 

32.6 

32-7 

32.9 

33-o 

33'? 

33-3 

33.5 

33-6 

33.8 

33-5 

33-6 

33-7 

33-9 

34-0   34.2 

34-3 

34-5 

34-6 

34.8 

34-5 

34-6 

34-7 

34-9 

350 

35.2 

35-3 

35.5 

35-6 

35-8 

8S 


CORRECTIONS    FOR    TEMPERATURE. 


DEGREES  OF  THERMOMETER  (Fahren7ieit) 


!! 

66 

67 

68 

69 

70 

71 

72 

73 

74 

75 

IO2O 

20.5 

20.6 

20.7 

20  0 

21.  0 

21.  J 

21.2 

21.3 

21.5 

21.6 

21 

21.6 

21.7 

21.8 

22.0 

22.1 

22.2 

22.3 

22.4 

22.5 

22.6 

22 

22.6 

22.7 

22.8 

23.0 

23.1 

23.2 

23.3 

23.4 

23.5 

23-7 

23 

23.6 

23-7 

23.8 

24-0 

24-1 

24.2 

24-3 

24.4 

24.6 

24.7 

24 

24.6 

24-7 

24-9 

25-0 

25.1 

25.2 

25.3 

25-5 

25.6 

25.7 

'  25 

25.6 

25-7 

25-9 

26.0 

26.1 

26.2 

26.4 

26.5 

26.6 

26.8 

26 

26.7 

26.8 

270 

27-1 

27.2 

27-3 

27.4 

27.5 

27.7 

27.8 

27 

27-7 

27.8 

28.0 

28.1 

28.2 

28.3 

28.4 

28.6 

28.7 

28.9 

28 

28.7 

28.8 

29.0   29.1 

29.2 

29.4 

29.5 

29.7 

29.8 

29.9 

29 

29.8 

29-9 

30-1 

302 

30.3 

30.4 

30.5 

30-7 

30.9 

31.0 

30 

30.8 

30-9 

3i-J 

31.2 

31.3 

3L5 

3T.6 

31-8 

3L9 

32.1 

3i 

3i.8 

32.0 

32-2 

32.2 

32.4 

32.5 

32.6 

32.8 

33-o 

33.1 

32 

32-9 

33-0 

33-2 

33-3 

33-4 

33-6 

33.7 

33-9 

34-0 

34.2- 

33 

33-9 

34.o 

34-2 

34-3 

34-5 

34-6 

34-7 

34-9 

35-i 

35-2 

34 

34-9 

35.o 

35-2 

35-3 

35-5 

35.6 

35-8 

36-0 

36.1 

36.3, 

35 

35-9 

36-1 

36.2 

36-4 

36.5 

36.7 

36-8 

37-0 

37-2 

37-3- 

84 


TOTAL   SOLIDS   CALCULATED. 


(B) 

TOTAL    SOLIDS    CALCULATED    FROM    FAT    AND 

SPECIFIC  GRAVITY,  BY  THE  FORMULA 

OF  HEHNER  &  RICHMOND. 


.859  T  --  .2186  G  —  .05    (  -  —  2.5   ) 

if  positive. 


Differences : 

.01  Fat         =  .01  Total  Solids. 
.1     Sp.  Gr.  =  .025     "         " 


FAT 


i 

I.I 

1.2 

1-3 

1.4 

I-5 

1.6 

i-7 

1.8 

i-9 

q.  -iS 

Q.^O 

063 

9.7*5 

9.87 

Q  QQ 

9c  i 

q6l 

9.76 

9.88 

IO  OO 

IO  II 

•5 

9.64 

9-77 

9.89 

IO.OI 

10.13 

10.25 

•32  O 

977 

Q.QO  IO.O2 

10.14 

10.26 

T<~»   17 

Q  QI 

IO.O1 

10.15 

10.27 

IO.  "^Q  lO.'JO 

33-0 

10.04 

io.  16 

10.28:10.40 

IO.5ijlO.63 

•5       9-71 

9-83 

9.95  10.  06 

IO.I7 

10.30 

10.41  10.52 

10.64  10.76 

34-0 

9.84    9.9610.0810.1910.30 

10.43 

10.54:10-65 

10.78  10.88 

•  5 

9-97110.09  10.21  10.33  10.44 

10.56  10.67  10.78 

10.90  n.oi 

35-0 

IO.  IO 

10.22  10.34  10.46  10  57 

10.69  10.80'  10.91 

11.03,11.14 

85 


TOTAL  SOLIDS  CALCULATED. 


Sp.  Gr. 

FAT 

2 

2.1 

2.2 

2-3 

2.4 

2.5 

2.6 

2-7 

2.8 

2-9 

1024.0 

8.42 

8-54 

8.66 

8-77 

8.89 

9.01 

9.12 

9-24 

9-35 

9-47 

-5 

8.56   8.68 

8-79 

8.90     9.02 

9.14 

925    9-37 

9.48 

9.60 

25.0 

8.68   8.80   8.91    9.02    9.14 

9.26 

9-37    9-49 

9.60 

9.72 

-5 

8.81 

8.93     9.04     9,15     927 

9-39!  9-50 

9.62 

9-73 

9-85 

26.0 

8.94 

9.06     9.17 

9.28     9.40 

9-52 

9-63 

9-75 

9.86 

9.98 

•5 

9.06 

9.18 

9.29 

940     9.52 

9.64 

9-75 

9.87 

9.98 

10.  10 

27.0 

9.19 

9-31    9-42    9-53   9-65 

9-77    9-88 

10.00 

10.  1  1 

10.23 

-5 

9-32 

9-44   9-55    966:  9.78 

9.90  10.01 

10.13 

10.24 

10.36 

28.0 

9-45    9-57    9-68    9.79    9-9* 

10.03 

10.14 

io.26;io.37 

10.49 

-5 

9-57 

9.69 

9.80    991  10.04  10.1610.27  10.38 

10.49 

10.61 

29.0 

9.70 

9.82 

9.93  10.04  10.16  10.30  10.39  10.51 

10.62 

10.74 

•5 

9-83 

9-95 

10.  06 

IO.I8  10.29  10.42  10.52  10.64 

10-75 

10.87 

30.0 

9.96 

10.  og1  10.  20'  10  31  10.42'  10.54  10.  65'  10.77 

10.88 

I  LOO 

.5        10.10  10.21  10-33  10.44  10.55  10.67  10.78  10.90 

II.  01 

II-I3 

31.0      |l0.23I0.34|l0.46l0.57 

10.68  10.  80  10.91  11.03 

11.14 

11.26 

.5        10.36  10-47  10.58  10.69  10.80  10.92  11.03  H.I5 

11.26 

11.38 

32.0      10.49  10.  60  10.71  10.83  10  93;ii.05  ii.  16 

11.28 

ii-39 

H.5I 

.5      10.61 

10.72 

10.84  10.96 

ii.  06 

ii.  18  11.29 

11.41 

11.52 

11.64 

33.0      10.74 

10.85 

io.97Jn.o9 

11.19 

11.31  11.42 

11-54 

11.65 

n-77 

-5 

10.87 

10.98 

11.09  IT.  21 

11.32 

11-44 

11-55 

11.66 

11.77 

11.89 

34-o 

11.00  II.  II 

11.22 

n-34 

ii-44 

11.56 

11.67 

ii-79 

11.90 

12.02 

•  5 

11.1311.2411.35 

ii-47 

ii-57 

11.69  n.8o 

11.92 

12.03 

12.15 

35-o 

11.25  n.37!n.47  n-59  ii  69  n-8i  11.92 

12.04 

12.15 

12.27 

TOTAL  SOLIDS  CALCULATED. 


Sp.  Gr. 

FAT 

! 

3- 

3-i 

3-2      3-3 

3.4 

3-5 

3-6 

3-7 

3-8 

3-9 

1024.0 

9-59 

9.70 

9.82 

9-94 

10.05 

10.17 

,o.a9 

10.40 

10.52 

10.63 

•  5 

9.72 

9-83 

9-95 

10.07  10.18  10.30 

10.42 

10-53 

10.65 

10.76 

25.0 

9.84 

9-95 

10.07 

10.19 

10.30 

10.42 

10.54 

10.65 

10.77 

10.88 

•5 

9-97 

10.08 

10.20 

10.32 

1043 

10.55 

10.67 

10.78 

10.90 

II.  01 

26.0 

IO.IOTO.2I 

10.33 

10.45 

10.56 

10.68 

10.80 

10.91 

11.03 

11.14 

•5 

IO.22 

10.33 

10.45 

1057 

10.68 

10.80 

10.92 

11.03 

11.15 

11.26 

27.0 

10.35 

10.46 

1058 

10.70  10.81 

10.93 

11.05 

ii.  16 

11.28 

11-39 

•5 

1048  10-59  10.71 

10.83  I0"94 

ii.  06 

II.I8 

11.29 

11.41 

11.52 

128.0 

10.61  10.72  10.84  io.96!n.o7 

11.19 

11.31 

11.42 

11-54 

11.65 

•5 

10.73  10.841  10.  96;  1  1  08  11.19 

11.31 

n-43 

H.54 

Ti.66 

11.77 

29.0 

10.86  10.97 

II.  09,11.  21  11.32  11-44 

11.56 

11.67 

11.79 

11.90 

•5 

10.99 

II.  10 

11.22 

11.34  H.45  1"-57 

11.69 

ii.  80 

11.92 

12.03 

30.0 

II.  12 

11.2311.35 

11.4711.58 

11.70 

11.82 

11.93 

12.05 

12.  l6 

•5 

11.25  11.3611.48 

ii.  60  11.71 

11.83 

n-95 

12.06 

12.18 

12.29 

31.0 

11.38  11.49 

II.  6l 

11.73  11.84 

11.96 

12.08 

12.19 

12.31 

12.42 

•5 

11.50  ii.  61 

II.73U.85II.96 

12.08 

1  2.  2O 

12.31 

12.43 

12.54 

32.0 

11.63111.74 

11.86  11.98  12.09 

12.21 

12-33 

12.44 

12.56 

12.67 

•5 

11.76 

11.87 

11.99  12.11:12.22 

12.34 

12.46 

12-57 

12.69 

12.80 

33-0 

11.89 

12.00 

I2.I2jI2.24  12.35 

12.47 

12.59 

12.70 

12.82 

12.93 

.5 

12.01 

12.12 

12.24  12.36 

12.47 

12.59 

12.71 

12.82 

12.94 

13-05 

34-0 

12.14 

12.25 

12.3712.49 

12.60 

12.72 

12.84 

12-95 

13.07 

13.18 

.5 

12.27 

12.38  12.50  12.62 

12.73  12-85 

12.97 

13.08 

13.20 

13.31 

35.o 

12.39 

12.50  12.62112.74  12  85!i2.97 

13.09 

13.20 

I3-32 

13.43 

87 


TOTAL  SOLIDS  CALCULATED. 


FAT 


LJ.    \Jti  . 

4.0 

4.1 

,a 

4-3 

4-4 

4-5 

4.6 

4-7 

4.8 

4-9 

>24.0 

10.75 

10.87 

10.98 

II.-IO 

11.22 

H-33 

n-45 

11-57 

11.68 

11.80 

•5 

10.88 

II.  OO  1  1.  1  1 

11.23 

n-35 

11.46 

11.58 

11.70 

ii.  81 

H-93 

25.0 

11.00 

II.  12  TI.23 

it-  35 

11.47 

11.58 

11.70 

[1.82  11.93 

12.05 

•5 

11.13 

ii.25ln.36 

11.48 

ii.  60 

11.71 

11.83 

11.95  12.06 

12.17 

26.0 

11.26 

11.3811.49 

.11.61 

n-73 

11.84 

11.96 

12.08  12.19 

12.30 

-5 

11.38 

31.50  11.61  ii  73 

11.85 

11.96 

I2.0S 

12.20  12.31 

12.42 

27.0 

11.51 

11.63  ii  74  11.86 

11.98 

12.09 

12.21 

12.33  12.44 

12.55 

-5 

11.64 

11.76111.87 

11.9912.11 

12.22 

12.34  12.46 

12.57 

12.68 

28.0 

11.77 

11.89  12.  OO  12.12  12.24 

12-35 

12.47 

12.59 

12.70 

12.81 

-5 

11.89 

12.01 

12.12 

1224 

12.36 

12.47 

12.59 

12.71 

12.82 

12.93 

29.0 

12.  02  12.14  12.25 

12.37 

12.49 

1  2.  60 

12.72 

12.84 

12.95 

13.06 

•5 

12.15  12.27  12.38  12.50 

12.  6l 

12.73 

12.85 

12.97 

13-08 

13.19 

30.0 

12.28 

12.4012.51 

12.63 

12.74 

12.86 

12.9813.10 

13-21 

13-32 

•5 

12.41 

12.53 

12.64  12.76  I2.87|I2.99 

13.11 

13-23 

13.34 

13-45 

31.0 

12.54  12.66 

12.77  12.89  13.00 

13.12 

13-24 

I3.36 

13.47 

13-58 

-5 
32.0 

12.66 
12.79 

12.78 
12.91 

[2.89I3.0I   13.12,13.24 
13.02  13.1413.25  13.37 

I3-36 
13.49 

13.48 
I3.6I 

13.59 
13.72 

13.70 
13.83 

•  5 

12.92 

13-0413  15  13.2713-38 

13-50 

13.62 

13-74 

13-85 

13.96 

33-0 

13-05 

J3-I7 

13.2813.40 

13.51 

13-63 

13.75 

13.87 

13.98 

14.09 

•5 

I3-I7 

13.29 

13.40  13.52 

13-63 

13.75 

13.87 

13-99 

14.10 

14.21 

34-0 

13-30 

13-42 

I3.53'I3-65 

13.76 

13.88  14.00 

14.12 

14.23 

14-34 

.5 

13.43 

J3.55  13-66  13.78113.89 

14.01 

U.I3 

14-25 

14.36 

14.47 

35-o 

!3-55  13.67113.78  13-901401 

I4-I3 

14-25 

14.37  14.48 

14-59 

j          1 

88 


TOTAL  SOLIDS  CALCULATED. 


Sp.  Gr. 

FAT 

5-o 

5-1 

5-2 

5-3 

5-4 

5.5 

5.6 

5-7 

5-8 

5-9 

1024.0 

11.91 

12.03 

12.15 

12.26 

12.30  12.50 

12.61 

12.73,12.85 

12.96 

•5 

12.04 

12.  l6 

12.28 

12.39 

12.51  12.63  12.74 

12.86 

12.98 

13.09 

25.0 

12.  l6 

12.28 

12.40 

12.51 

12.63  J2.75 

12.86 

£2.98  13.10 

13.21 

•5 

12.29 

12.41 

12.53 

12,64 

12.7612.88 

12.99 

13-1113.23 

J3.34 

26.0 

12.42 

12.54  12.66 

12.77 

12.89  13.01 

13.12 

13.24  13.36 

13-47 

•5 

12.54 

]2.66 

12.78 

12  89 

13.01  13.13 

13-24 

I3'36|I3-48 

13-59 

27.0 

12.67 

12.79 

12.91 

13.02 

13.14  13.26 

13-37 

13.4913.61 

13.72 

.5 

1  2.  80 

12.92 

13.04 

I3-I5 

13.27  13.39 

13-50 

13.62 

13-74 

13-85 

28.0 

12  93  13-05 

13-17 

13.28 

13.40  13.52 

13.63 

13-75  13-87 

13-98 

.^ 

*3-°5 

I3-I7 

13.29 

1340 

13.52  13.64 

13.75 

13-87  13.99 

14.10 

29.0 

13.18 

13-30 

13-42 

13-53 

13.65  13.77 

13-88 

14.00.14.12 

14-23 

•5 

13.31  13.43 

13.55 

13.66 

13.78  13.90 

14.01 

14.13  14.25 

14.36 

30.0 

13-44^3.56 

13.68 

J3.79 

13.91 

14.03 

14.14 

14.26  14.38 

14.49 

•5 

13-57  13-69 

13.81 

13.92 

14.04 

14.16 

14.27 

H.39 

H.5I 

14.62 

. 

31.0 

13.7013.82 

J3-94 

14.05 

14.17 

14.29 

14.40 

I4-52 

14.64 

H-75 

.5 

13.82  13.94 

14.06  14.17 

14.29 

14.41 

14-52 

14.64 

14.76 

14.87 

32.0 

13.9514.07 

14.19 

14.30 

14.42 

14.54 

14.65 

'14.77  J4-89 

15.00 

•5 

14.08  14.20 

14-32 

14.43 

,14.55 

14.67 

14.78 

14.90  15.02 

15-13 

33-o 

14.21  14.33 

H-45 

14.56 

14.68 

14.80 

14.91 

15.0315-15 

15.26 

•5 

14.33^14.45 

14.57 

14.68 

'14.80 

14.92 

15.03 

15-15  J5-27 

15-38 

34-o 

14.46  14.58 

14.70 

14.81  114.93 

15.05 

15.16  15.28 

15.40 

i5-5i 

•  5 

14.5914.71 

14.83 

!i4-94 

15.06 

15.18 

15.2915.41  15.53 

15.64 

i 

35.0     JI4.7I  14.83 

14-95 

15.06 

15.18 

15.30 

.15.41 

!i5-53  15.65 

15-76 

\          < 

89 


TOTAL  SOLIDS  CALCULATED. 


FAT 

1  6.0. 

6.1 

6.2 

6.3  |  6.4 

6.5 

" 

6.6 

6.7     6.8     6.9 

1024.0     ,  13.08  13.20 

13.31 

134213.54 

13.66 

13-78 

13.90:14.01 

14-13 

•  5      I3-2113-33 

13.44 

•3-55  13-67  13-79  13-91 

14.0314.14 

14.26 

25.0      13-33  13-45 

^3-56 

i3-67^3.79 

13-91 

14.03 

[4.1514.2614.38 

.5      13.46 

13.58 

13.69!  13.80  1  13.92 

14.04 

14.16 

14.28 

14-39  I4-5I 

26.0      13.59 

T3.7ijJ3.82 

13.93  14-05 

14.17 

14.29 

14.41 

H.52 

14.64 

.5      '3-72 

13-83 

13-94 

1405  14.17 

14.29 

14.41 

14-53 

14.64 

14.76 

27.0     13.84 

13.96 

1407 

14.18  14-30 

14.42 

14-54 

14.6614.77 

14.89 

•  5 

13.97  14.09  14.20 

M  31  J4-43 

14-55 

14.67 

14.79 

14.90 

15.02 

28.0 

14  10 

14.22 

14-33 

14.  44;  14.  56 

14.68 

14.80 

14.92 

15-03 

I5.15 

.5 

14.22 

14-34 

1445 

1456  14.68 

14.8014.92 

15.04 

I5.I5 

15-27 

29.0      14.35 

14-47 

14.58 

14.69  14.81 

14-93 

15-05 

15.17 

15.28 

15.40 

•5 

14.48 

14.60 

14.71  14.82  14.94 

15.06 

15.18 

15-30 

I54I 

15.53 

30.0 

14,61 

14-73 

1484 

14.95  15.07 

15-19 

I5-31 

15-43 

15.54  15-66 

•5 

14.74 

14.86  14.97 

15.0815.20 

15-32 

15-44 

15-56 

15.67 

15-79 

31.0     14.87 

14.99 

15.10 

15-21  15.33 

15.45 

15-57 

15.69  15.80 

15.92 

.5      14.9915." 

15.22 

I5-33I545 

15-57 

15.69 

15.81  15.92 

16.04 

32-0 

15.12 

I5.24U5.35 

15-46:15.58 

15.7015.82 

15.9416.05  16.17 

•5 

15-25  15-37 

15.48 

15.59^5.71 

-15-83 

15.95 

16.07  16.  18  16.30 

33-0 

15-38  15.50 

15.61 

115.72  15.84 

I5-96 

1  6.  08 

16.20  16.31  16.43 

•5 

15.50 

15-62 

15.7315.8415.96 

!i6.oS 

16.20  16.32 

16.43 

16.55 

34-0 

15-63 

15.75 

I5.86li5-97j6.09  16.21 

i6.33 

16.45 

16.56  16.68 

•5 

15-76 

15.88 

15.99  16.  1016  22  16.33 

16.46 

16.5816.6916.81 

35.o      15.88 

i6.ooi6.ii 

16.22  16.34  16.45 

I          I          i 

16.58 

16.70  16.81 

16.92 

As  already  noted  on  page  13,  the  heating  of  milk  causes  an 
alteration  in  the  milk  sugar.  In  The  Analyst  for  June  and  July, 
1893,  H.  D.  Richmond  and  L.  K.  Bosely  note  that  heating  to 
the  extent  to  which  milk  is  subjected  in  the  preparation  of  con- 
densed milk  may  reduce  the  rotatory  power  of  the  sugar  suffi- 
ciently to  cause  serious  error,  if  the  polarimeter  be  used  for  the 
determination.  The  reducing  power  with  Fehling's  solution  is 
not  seriously  affected. 

In  the  examinations  made  by  us,  we  have  not  noticed  so  great 
an  alteration  in  the  milk  sugar,  but  in  view  of  the  liability  to 
error  from  this  cause,  the  cane  sugar  is  best  determined  by 
the  difference  in  polarimetric  reading  produced  by  inversion, 
(pp  60-62)  and  the  milk  sugar  gravi metrically  (p  62). 

The  albumin  ^of  condensed  milk  is  partly  coagulated  by  the 
heat  employed  in  its  manufacture.  When  magnesium  sulfate 
is  added,  therefore,  to  precipitate  the  casein,  the  coagulated  al- 
bumin will  be  carried  down  at  the  same  time  and  only  the  solu- 
ble albumin  will  be  found  in  the  filtrate.  Faber  ( Analyst,  1889) 
has  applied  this  fact  to  the  detection  of  the  previous  heating  of 
a  sample  of  milk.  Usually,  only  about  one-third  of  the  albu- 
min is  found  uncoagulated  in  condensed  milk.  The  soluble 
albumin  of  unheated  milk  ranges  from  0.35  to  0.50  per  cent. 


laicuiauoii  meiuuu,  ^o — 

Calf's  brain  in  milk,  43  T/JELDAHL-GUNNING 

Cane-sugar,  43,  6l  J\        Method,  30 
Casein  in  milk,  10,  33 

butter,  65  I  ACTOCRITE,  24 

cheese,  77  L     Lactodensimeter,  16 

91 


INDEX. 


n  BNORMAL  milks,  51/52 
*•     Adam's  method,  20 
Adulterants,  41 
Albumin,  10 

,  determination  of,  33 

Amphoteric  reaction,  12 
Annatto,  42 
Antiseptics,  43 
Ash  of  butter,  65 

cheese,  76 

—  milk,  10,  19 
Average  of  solids,  47 

OACTERIA  in  milk,  12 
*-^     Benzoic  acid,  44 
Birotation,  40 
Black  pepsin,  63 
Boiling,  effects  of,  13 
Borax,  43,  45 
Boric  acid,  43,  45 
Butter,  63 

,  analysis  of,  64 

colors,  75 

substitutes,  65 

Buttermilk,  14 

PALCIUM  phosphate  in 
^        milk,  10 
Calculation  method,  28 
Calf's  brain  in  milk,  43 
Cane-sugar,  43,  61 
Casein  in  milk,  10,  33 

butter,  65 

cheese,  77 


Caseinogen,  10 
Cheese,  75,  78 
Citric  acid,  10 
Coal-tar  colors,  42 
Colostrum,  n 
Condensed  milk,  60 
Cream,  14 
,  evaporated,  60 

HAT  A  for  milk  inspection,  47 
u     Decomposition  of  milk,  13 
De  Leval  Method,  24 
Diphenylamin  test,  41 
Diseases  conveyed  by  milk,  45 

CNZYMES  in  milk,  10 
*"     Evaporated  cream,  60 

CAT  in  butter,  64 

Fat  in  cheese,  77 
Fat  in  milk,  20 
Fehling's  solution,  36 
Formula  for  fat,  29 
Freezing,  effect  of,  13 

GLOBULIN  in  milk,  10 
^     Glycerol-soda,  67 

(JEHNER  &  RICHMOND'S 
formula,  29 

T/JEIvDAHL-GUNNING 
**        Method,  30 

T  ACTOCRITE,  24 

L    Lactodensimeter,  16 


91 


92 


INDEX. 


Lactose,  9 

,  determination  of,  36,  41 

Leffmann-Beani  method,  26 

MARGARINE,  65 
1V1     Mercuric  nitrate  solu- 
tion. 38 

Microbes  in  milk,  12,  56 
Milk  control,  42 

,  coagulation  of,  10 

,  formation  of,  9 

globules,  9 

,  properties  of,  12 

proteids,  of,  10 

standards,   15,  51 

-   sugar,  .9 

— ,  composition  of,  n 

MITRATESinmilk,  41 
1  *     Nostrums  for  butter  mak- 
ing, 63 

QLEOMARGARIN   65 

DEPSIN,  black,  63 
Polarimeters,  39 
Poor  milk,  causes  of,  51 
Proteids,  30 
Pyknometer,  17 

DEICHERT-WOLLNY 
1V         Method,  66 
Richmond  slide  rule,  29 
Ritthausen  Method,  34 

q  ALICYLIC  acid,  46 

^     Salt,  43 
Sanitary  relations,  54 
Seasonal  variations  in  milk,  41, 
47,  48,  50,  51,  53 


Skimmed  milk,  55 
Skimming,  15 

— ,  centrifugal,  14 
Sodium  carbonate,  43 
Society  of  Public  Analysts' 

standard,  50,  53 
Solids,  deficient,  51 
Solids,  excessive,  52 
Spirillum  cholerae  in  milk,  12 
Soxhlet,    composition   of 

milk,  47 
Specific  gravity,  15 

bottle,  17 

of  milk,  change 

in,  12 

Standards,  official,  54. 
Starch,  43 
Sterilization,   12,  56 

,  fractional,  56 

Sugar,  cane,  43,  61 
,  milk,  9,  36 

TOTAL  solids,  17 
A      Turmeric,  42 

VARIATIONS  in  milk,  47,  54 
*      Vieth  on  milk  standards,  51 
Vieth,  table  of  averages,  47 
Volatile  acids  in  butter,  66 

,    Leffmann-Beam 

method  for,  66 

— ,  official  method 
for,  70 

WATER  in  butter,  64 

Water  in  cheese,  76 
Water  in  milk,  41 
Werner-Schmid  method,  23 
Westphal  balance,  16 


CATALOGUE   No.  7. 


OCTOBER,   1893. 


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No.  1.     SURGERY.    318  Illustrations. 

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WALSH  AM,  M.D.,  Asst.  Surg.  to,  and  Demonstrator  of 

Surg.   in,  St.   Bartholomew's  Hospital,  London,  etc. 

318  Illustrations. 

Presents  the  introductory  facts  in  Surgery  in  clear,  precise 
language,  and  contains  all  the  latest  advances  in  Pathology, 
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"  It  aims  to  occupy  a  position  midway  between  the  pretentious 
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NEW    EDITION. 

The  Diseases  of  Women.  Including  Diseases  of  the 
Bladder  and  Urethra.  By  DR.  F.  WINCKEL,  Professor 
of  Gynaecology  and  Director  of  the  Royal  University 
Clinic  for  Women,  in  Munich.  Second  Edition.  Re- 
vised and  Edited  by  Theophilus  Parvin,  M.D., 
Professor  of  Obstetrics  and  Diseases  of  Women  and 
Children  in  Jefferson  Medical  College.  150  Engrav- 
ings, most  of  which  are  original. 
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satisfactory  one  to  put  into  the  hands  of  students.     It  is  issued  in  a 

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Medical  and  Surgical  Journal . 

No.  3.    OBSTETRICS.    227  Illustrations. 
A  Manual  of  Midwifery.     By  ALFRED  LEWIS  GALABIN, 
M.A.,  M.D.,  Obstetric  Physician  and  Lecturer  on  Mid- 
wifery and  the  Diseases  of  Women  at  Guy's  Hospital, 
London;     Examiner   in    Midwifery   to   the   Conjoint 
Examining  Board  of  England,  etc.     With  227  Illus. 
"  This  manual  is  one  we  can  strongly  recommend  to  all   who 
desire  to  study  the  science  as  well  as  the  practice  of  midwifery. 
Students   at  the  present  time  not  only  are  expected  to  know  the 
principles  of  diagnosis,  and  the  treatment  of  the  various  emergen- 
cies and  complications  that  occur  in  the  practice  of  midwifery,  but 
find  that   the  tendency  is  for  examiners  to  ask  more  question* 
relating  to  the  science  of  the  subject  than  was  the  custom  a  few 
years   ago.  *  *  *    The  general  standard  of  the  manual  is  high ; 
and  wherever  the  science  and  practice  of  midwifery  are  well  taught 
it  will  be  regarded  as  one  of  the  most  important  text-books  on  the 
subject." — London  Practitioner. 

No.  4.    PHYSIOLOGY.    Sixth  Edition. 

254  ILLUSTRATIONS  AND  A  GLOSSARY. 
A  Manual  of  Physiology.  By  GERALD  F.  YEO,  M.D., 
F.R.C.S.,  Professor  of  Physiology  in  King's  College, 
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This  volume  was  specially  prepared  to  furnish  students  with  a. 
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B'aced  it  in  the  list  of  text-books  recommended  in  the  circular  of  the 
niversity  Medical    College." — Prof.   Lewis  A.  Stitnson,  M.D., 
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No.  5.    DISEASES  OP  CHILDREN. 

SECOND  EDITION. 

A  Manual.  By  J.  F.  GOODHART,  M.D.,  Phys.  to  the 
Evelina  Hospital  for  Children;  Asst.  Phys.  to 
Guy's  Hospital,  London.  Second  American  Edition. 
Edited  and  Rearranged  by  Louis  STARR,  M.D.,  Clinical 
Prof,  of  Dis.  of  Children  in  the  Hospital  of  the  Univ. 
of  Pennsylvania,  and  Physician  to  the  Children's  Hos- 
pital, Phila.  Containing  many  new  Prescriptions,  a  list 
of  over  50  Formulae,  conforming  to  the  U.  S.  Pharma- 
copoeia, and  Directions  for  making  Artificial  Human 
Milk,  for  the  Artificial  Digestion  of  Milk,  etc.  Illus. 

"  The  author  has  avoided  the  not  uncommon  error  of  writing  a 
book  on  general  medicine  and  labeling  it  '  Diseases  of  Children,' 
but  has  steadily  kept  in  view  the  diseases  which  seemed  to  be 
incidental  to  childhood,  or  such  points  in  disease  as  appear  to  be  so 
peculiar  to  or  pronounced  in  children  as  to  justify  insistence  upon 
them.  *  *  *  A  safe  and  reliable  guide,  and  in  many  ways 
admirably  adapted  to  the  wants  of  the  student  and  practitioner." — 
American  Journal  of  Medical  Science. 

No.  6.    MATERIA  MEDICA,  PHARMACY, 
PHARMACOLOGY,  AND  THE- 
RAPEUTICS. 

JUST  READY. 

A   Handbook  for   Students.     By  WM.  HALE  WHITE, 
M.D.,  F.R.C.P.,  etc.,  Physician  to,  and  Lecturer  on  Ma- 
teria  Medica,  Guy's  Hospital ;    Examiner  in  Materia 
Medica,  Royal  College   of   Physicians,   London,  etc. 
American  Edition.    Revised  by  REYNOLD  W.  WILCOX, 
M.A.,  M.D.,  Prof,  of  Clinical  Medicine  at  the  New  York 
Post-Graduate  Medical  School  and  Hospital ;  Assistant 
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much  new  material.     Dr.  Wilcox's  long  experience  in  teaching 
and  writing  on  therapeutical  subjects  particularly  fits  him  for  the 
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ing a  very  complete  handbook,  containing  much  minor  useful  in- 
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No.  7.    MEDICAL  JURISPRUDENCE  AND 
TOXICOLOGY. 

THIRD  REVISED  EDITION. 

By  JOHN  J.  REESE,  M.D.,  Professor  of  Medical  Jurispru- 
dence and  Toxicology  in  the  University  of  Pennsyl- 
vania ;  President  of  the  Medical  Jurisprudence  Society 
of  Phila. ;    Third  Edition,  Revised  and  Enlarged. 
"  This  admirable  text-book."— A mer.Jour.  of  Med.  Sciexees. 
"  We  lay  this  volume  aside,  after  a  careful  perusal  of  its  pages, 
with  the  profound  impression  that  it  should  be  in  the  hands  of  every 

doctor  and  lawyer.     It  fully  meets  the  wants  of  all  students 

He  has  succeeded  in  admirably  condensing  into  a  handy  volume  all 
the  essential  points." — Cincinnati  Lancet  and  Clinic. 

No.  8.    DISEASES  OP  THE  EYE.    176Illus. 

FOURTH  EDITION.  JUST  READY. 
Diseases  of  the  Eye  and  their  Treatment.  A  Handbook 
for  Physicians  and  Students.  By  HENRY  R.  SWANZY, 
A.M.,  M.B.,  F.R.C.S.I.,  Surgeon  to  the  National  Eye  and 
Ear  Infirmary;  Ophthalmic  Surgeon  to  the  Adelaide 
Hospital,  Dublin;  Examiner  in  Ophthalmic  Surgery 
in  the  Royal  University  of  Ireland.  Fourth  Edition, 
Thoroughly  Revised.  176  Illustrations  and  a  Zephyr 
Test  Plate.  500  pages. 

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current  and  modern  information  that  will  prove  alike  beneficial  to 
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WITH  ILLUSTRATIONS.  JUST  READY. 
Lectures  on  Mental  Diseases,  designed  for  Medical  Stu- 
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Hartford  Retreat,  Lecturer  on  Mental  Diseases  in  Yale 
University,  New  Haven,  Conn.,  Hon.  Mem.  British 
Psycho.  Asso'n,  etc.  With  Illustrations  and  a  Digest  of 
the  Laws  of  the  various  States  relating  to  the  Commit- 
ment and  Care  of  the  Insane.  636  pages. 

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ANATOMY. 

Morris'  New  Text-Book  on  Anatomy.  Now  Ready.  By 
ten  leading  Surgeons  and  Anatomists,  and  Edited  by  Henry 
Morris,  F.R.C.S.  791  Specially  Engraved  Illustrations,  214  of 
which  are  printed  in  colors.  Octavo.  1280  pages. 

Price  in  Cloth,  7.50;  Sheep,  8.50  ;  Half  Russia,  9.50. 
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Macalister's  Human  Anatomy.  816  Illustrations.  A  new 
Text-book  for  Students  and  Practitioners,  Systematic  and  Topo- 
graphical, including  the  Embryology,  Histology,  and  Morphology 
of  Man.  With  special  reference  to  the  requirements  of 
Practical  Surgery  and  Medicine.  With  816  Illustrations, 
400  of  which  are  original.  Octavo.  Cloth,  7.50;  Leather,  8.50 

Ballou's  Veterinary  Anatomy  and  Physiology.  Illustrated. 
By  Wm.  K.  Ballon,  M.D.,  Professor  of  Equine  Anatomy  at  New 
York  College  of  Veterinary  Surgeons.  29  graphic  Illustrations. 
I2mo.  Cloth,  i.oo;  Interleaved  for  notes,  i.*5 

Holden's  Dissector.  A  manual  of  Dissection  of  the  Humaa 
Body.  Sixth  Edition.  Edited  by  A.  Hewson,  M.D.,  Demonstra- 
tor of  Anatomy  at  Jefferson  Medical  College.  Over  300  Illus- 
trations, many  of  which  are  new.  Octavo.  Nearly  Ready. 

Holden's  Human  Osteology.  Comprising  a  Description  of  the 
Bones,  with  Colored  Delineations  of  the  Attachments  of  the 
Muscles.  The  General  and  Microscopical  Structure  of  Bone  and 
its  Development.  With  Lithographic  Plates  and  Numerous  Illus- 
trations. Seventh  Edition.  8vo.  Cloth,  6.00 

Holden's  Landmarks,  Medical  and  Surgical.  4th  Ed.  Clo.,  1.25 

Potter's  Compend  of  Anatomy.  Fifth  Edition.  Enlarged. 
16  Lithographic  Plates.  117  Illustrations.  Seepage  14. 

Cloth,  i.oo;  Interleaved  for  Notes,  1.25 

CHEMISTRY. 

Hartley's  Medical  Chemistry.  Second  Edition.  A  text-book 
prepared  specially  for  Medical,  Pharmaceutical,  and  Dental  Stu- 
dents. With  50  Illustrations,  Plate  of  Absorption  Spectra  and 
Glossary  of  Chemical  Terms.  Revised  and  Enlarged .  Cloth ,  2 . 50 

Trimble.  Practical  and  Analytical  Chemistry.  A  Course  in 
Chemical  Analysis,  by  Henry  Trimble,  Prof,  of  Analytical  Chem- 
istry in  the  Phila.  College  of  Pharmacy.  Illustrated.  Fourth 
Edition,  Enlarged.  8vo.  Cloth,  1.50 

Bloxam's  Chemistry,  Inorganic  and  Organic,  with  Experiments. 
Seventh  Edition.  281  Illustrations.  Cloth,  4.50;  Leather,  5.50 
4»-  See  pages  a  to  5  for  list  of  Student*' Manuals . 


STUDENTS'  TEXT-BOOKS  AND  MANUALS.         7 

Chemistry  :— Continued. 

Richter's  Inorganic  Chemistry.  Fourth  American,  from  Sixth 
German  Edition.  Translated  by  Prof.  Edgar  F.  Smith,  PH.D. 
89  Wood  Engravings  and  Colored  Plate  of  Spectra.  Cloth,  2.00 

Richter's  Organic  Chemistry,  or  Chemistry  of  the  Carbon 
Compounds.  Illustrated.  Second  Edition.  Cloth,  4. 50 

Symonds.  Manual  of  Chemistry,  for  the  special  use  of  Medi- 
cal Students.  By  BRANDRHTH  SYMONDS,  A.M.,  M.D.,  Asst. 
Physician  Roosevelt  Hospital,  Out- Patient  Department ;  Attend- 
ing Physician  Northwestern  Dispensary,  New  York.  Cloth,  2.00 

Leffmann's  Compend  of  Chemistry.    Inorganic  and  Organic. 
Including  Urinary  Analysis.     Third  Edition.     Revised. 
See  page  13.  Cloth,  i.oo;   Interleaved  for  Notes,  1.25 

Leffmann  and  Beam.  Progressive  Exercises  in  Practical 
Chemistry.  i2mo.  Illustrated.  .  Cloth,  i.oo 

Muter.  Practical  and  Analytical  Chemistry.  Fourth  Edi- 
tion. Revised,  to  meet  the  requirements  of  American  Medical 
Colleges,  by  Prof.  C.  C.  Hamilton.  Illustrated.  Cloth,  1.25 

Holland.  The  Urine,  Common  Poisons,  and  Milk  Analysis, 
Chemical  and  Microscopical.  For  Laboratory  Use.  Fourth 
Edition,  Enlarged.  Illustrated.  Cloth,  i.oo 

Van  Niiys.    Urine  Analysis.    Illus.  Cloth,  2.00 

CHILDREN. 

Goodhart  and  Starr.  The  Diseases  of  Children.  Second 
Edition.  By  J.  F.  Goodhart,  M.D.,  Physician  to  the  Evelina 
Hospital  for  Children;  Assistant  Physician  to  Guy's  Hospital, 
London.  Revised  and  Edited  by  Louis  Starr,  M.D.,  Clinical 
Professor  of  Diseases  of  Children  in  the  Hospital  of  the  Univer- 
sity of  Pennsylvania;  Physician  to  the  Children's  Hospital, 
Philadelphia.  Containing  many  Prescriptions  and  Formula, 
conforming  to  the  U.  S.  Pharmacopoeia,  Directions  for  making 
Artificial  Human  Milk,  for  the  Artificial  Digestion  of  Milk,  etc. 
Illustrated.  Cloth,  3.00;  Leather,  3.50 

Hatfield.  Diseases  of  Children.  By  M.  P.  Hatfield,  M.D., 
Professor  of  Diseases  of  Children,  Chicago  Medical  College. 
Colored  Plate.  i2mo.  Cloth,  i.oo;  Interleaved,  1.25 

Starr.  Diseases  of  the  Digestive  Organs  in  Infancy  and 
Childhood.  With  chapters  on  the  Investigation  of  Disease, 
and  on  the  General  Management  of  Children.  By  Louis  Starr, 
M.D.,  Clinical  Professor  of  Diseases  of  Children  in  the  Univer- 
sity of  Pennsylvania.  Illus.  Second  Edition.  Cloth,  2.25 
4®-  See  pages  14  and  if  for  list  off Quiz-  Contpendsf 


8          STUDENTS'  TEXT-BOOKS  AND  MANUALS. 

DENTISTRY. 

Fillebrown.  Operative  Dentistry.  330  Illus.  Cloth,  2.59 
Flagg's  Plastics  and  Plastic  Filling.  4th  Ed.  Cloth,  4.00 
Gorgas.  Dental  Medicine.  Fourth  Edition.  Cloth,  3.50 

Harris.  Principles  and  Practice  of  Dentistry.  Including 
Anatomy,  Physiology,  Pathology,  Therapeutics,  Dental  Surgery 
and  Mechanism.  Twelfth  Edition.  Revised  and  enlarged  by 
Professor  Gorgas.  1028  Illustrations.  Cloth,  7.00  ;  Leather,  8.00 
Richardson's  Mechanical  Dentistry.  Fifth  Edition.  569 
Illustrations.  8vo.  Cloth,  4.50;  Leather,  5.50 

Sewill.    Dental  Surgery.    200  Illustrations.    3d  Ed.   do.,  3.00 
Taft's  Operative  Dentistry.    Dental  Students  and  Practitioners. 
Fourth  Edition.     100  Illustrations.       Cloth,  4.25  ;  Leather,  5.00 
Talbot.     Irregularities  of  the  Teeth,  and  their  Treatment. 
Illustrated.     8vo.     Second  Edition.  Cloth,  3.00 

Tomes'  Dental  Anatomy.     Third  Ed.     191  Illus.     Cloth,  4.00 
Tomes'  Dental   Surgery.     3d  Edition.    292  Illus.    Cloth,  5.00 
Warren.    Compend  of  Dental  Pathology  and  Dental  Medi- 
cine.    Illustrated,     ad  Ed.  Cloth,  i.oo;  Interleaved,  1.25 

DICTIONARIES. 

Gould's  New  Medical  Dictionary.  Containing  the  Definition 
and  Pronunciation  of  all  words  in  Medicine,  with  many  useful 
Tables  etc.  %  Dark  Leather,  3.25  ;  ^  Mor.,  Thumb  Index,  4.25 

Gould's  Pocket  Dictionary.  12,000  Medical  Words  Pro- 
nounced and  Denned.  Containing  many  Tables  and  an 
Elaborate  Dose  List.  Thin  64mo. 

Leather,  gilt  edges,  i.oo;  with  Thumb  Index,  1.25 

Harris'  Dictionary  of  Dentistry.  Fifth  Edition.  Completely 
revised  by  Prof.  Gorgas.  Cloth,  5.00;  Leather,  6.00 

Cleaveland's  Pronouncing  Pocket  Medical  Lexicon.  Small 
pocket  size.  Cloth,  red  edges  .75  pocket-book  style,  i.oo 

Lrongley 's  Pocket  Dictionary.  The  Student's  Medical  Lexicon, 
giving  Definition  and  Pronunciation,  with  an  Appendix  giving 
Abbreviations  used  in  Prescriptions,  Metric  Scale  of  Doses,  etc. 
24m o.  Cloth,  i.oo;  pocket-book  style,  1.25 

EYE. 

Hartridge  on  Refraction,    sth  Edition.    Illus.  Cloth,  2.00 

Swanzy.     Diseases  of  the  Eye  and  their  Treatment.    176 

Illustrations.     Fourth  Edition.  Cloth,  3  oo;  Leather,  3  50 

Fox  and  Gould.    Compend  of  Diseases  of    the   Eye  and 

Refraction.    2d  Ed.     Enlarged.     71  Illus.     39  Formulae. 

Cloth,  i.oo;  Interleaved  for  Notes,  1.25 
JKf  Seepages  2  to  5  for  list  of  Students'  Manuals. 


STUDENTS'  TEXT-BOOKS  AND  MANUALS.          9 

ELECTRICITY. 

Bigelow.    Plain  Talks  on  Medical  Electricity.  Cloth,  x.oo 

Mason's  Compend  of  Medical  Electricity.  Cloth,  x.oo 

Steavenson  and  Jones.    Medical  Electricity.  A  Practical 

Handbook.    Just  Ready.     Illustrated.     i2mo.  Cloth,  2.50 

HYGIENE. 

Coplin  and  Bevan.  Practical  Hygiene.  By  W.  M.  L.  Cop- 
lin,  Adjunct  Professor  of  Hygiene,  Jefferson  Medical  College, 
Philadelphia,  and  Dr.  D.  Bevan.  Illustrated.  In  Press. 

Parkes'  (Ed.  A.)  Practical  Hygiene.  Seventh  Edition,  en- 
larged. Illustrated.  8vo.  Cloth,  4.50 

Parkes'  (L.  C.)  Manual  of  Hygiene  and  Public  Health. 
Second  Edition.  i2mo.  Cloth,  2.50 

Wilson's  Handbook  of  Hygiene  and  Sanitary  Science. 
Seventh  Edition.  Revised  and  Illustrated.  Cloth,  3.25 

MATERIA  MEDICA  AND  THERAPEUTICS. 

Potter's  Compend  of  Materia  Medica,  Therapeutics,  and 
Prescription  Writing.  Fifth  Edition,  revised  and  improved. 
See  page  rf.  Cloth,  i.oo;  Interleaved  for  Notes,  1.25 

Davis.  Essentials  of  Materia  Medica  and  Prescription 
Writing.  By  J.  Aubrey  Davis,  M.D.,  Demonstrator  of  Obstet- 
rics and  Quiz-Master  on  Materia  Medica,  University  of  Penn- 
sylvania. i2mo.  Interleaved.  Net,  1.50 

Biddle's  Materia  Medica.  Twelfth  Edition.  By  the  late 
John  B.  Biddle,  M.D.  Revised  by  Clement  Biddle,  M.D.  8vo. 
Illustrated.  Cloth,  4.25;  Leather,  5.00 

Potter.  Handbook  of  Materia  Medica,  Pharmacy,  and 
Therapeutics.  Including  Action  of  Medicines,  Special  Thera- 
peutics, Pharmacology,  etc.  By  Saml.  O.  L.  Potter,  M.D., 
M.R.C.P.  (Lond.),  Professor  of  the  Practice  of  Medicine  in 
Cooper  Medical  College,  San  Francisco.  Fourth  Revised  and 
Enlarged  Edition.  776  pages.  8vo.  Cloth,  4.00;  Leather,  5.00 

"White  and  Wilcox.  Materia  Medica,  Pharmacy,  Phar- 
macology, and  Therapeutics.  A  Handbook  for  Students. 
By  Wm.  Hale  White,  M.D.,  F.R.C.P.,  etc.,  Physician  to  and 
Lecturer  on  Materia  Medica,  Guy's  Hospital.  Revised  by 
Reynold  W.  Wilcox,  M.D.,  Professor  of  Clinical  Medicine  at  the 
New  York  Post  Graduate  Medical  School,  Assistant  Physician 
Bellevue  Hospital,  etc.  American  Edition.  Clo.,  3.00;  Lea.,  3. 50 
49"  See  pages  14  and  13  for  list  of  t  Quit-  Contpends  t 


10       STUDENTS'  TEXT-BOOKS  AND  MANUALS. 

MEDICAL  JURISPRUDENCE. 

Reese.  A  Text-book  of  Medical  Jurisprudence  and  Toxi- 
cology. By  John  J.  Reese,  M.D.,  Professor  of  Medical  Juris- 
prudence and  Toxicology  in  the  Medical  Department  of  the 
University  of  Pennsylvania ;  Physician  to  St.  Joseph's  Hospital. 
Third  Edition.  Cloth,  3.00;  Leather,  3.50 

NERVOUS  DISEASES. 

Qowers.  Manual  of  Diseases  of  the  Nervous  System. 
A  Complete  Text- book.  By  William  R.  Gowers,  M.D.,  Prof. 
Clinical  Medicine,  University  College,  London.  Physician  to 
National  Hospital  for  the  Paralyzed  and  Epileptic.  Second 
Edition.  Revised,  Enlarged,  and  in  many  parts  Rewritten. 
With  many  new  Illustrations.  Octavo. 

VOL.  I.      Diseases  of  the  Nerves  and  Spinal  Cord.     616 
pages.  Cloth,  3.50 

VOL.  II.     Diseases  of  the    Brain  and  Cranial   Nerves. 
General  and  Functional  Diseases.  Cloth,  4.50 

Ormerod.  Diseases  of  Nervous  System,  Student's  Guide  to. 
By  J.  A.  Ormerod,  M.D.,  Oxon.,F.R.c.P.  (London),  Member  Path- 
ological. Clinical,  Ophthalmological,  and  Neurological  Societies, 
Physician  to  National  Hospital  for  Paralyzed  and  Epileptic  and 
to  City  of  London  Hospital  for  Diseases  of  the  Chest,  Demon- 
strator of  Morbid  Anatomy,  St.  Bartholomew's  Hospital,  etc. 
With  75  Wood  Engravings.  Cloth,  2.00 

OBSTETRICS  AND  GYNAECOLOGY. 

Davis.  A  Manual  of  Obstetrics.  By  Edw.  P.  Davis,  Clinical 
Lecturer  on  Obstetrics,  Jefferson  Medical  College,  Philadelphia. 
Colored  Plates,  and  130  other  Illustrations.  i2mo.  Cloth,  2.00 

Byford.  Diseases  of  Women.  The  Practice  of  Medicine  and 
Surgery,  as  applied  to  the  Diseases  and  Accidents  Incident  to 
Women.  By  W.  H.  Byford,A.M.,  M.D.,  Professor  of  Gynaecology 
in  Rush  Medical  College  and  of  Obstetrics  in  the  Woman's  Med- 
ical College,  etc.,  and  Henry  T.  Byford,  M.D.,  Surgeon  to  the 
Woman's  Hospital  of  Chicago.  Fourth  Edition.  Revised  and 
Enlarged.  306  Illustrations,  over  100  of  which  are  original. 
Octavo.  832  pages.  Cloth,  5.00  ;  Leather,  6.00 

Lewers'  Diseases  of  Women.  A  Practical  Text-book.  139 
Illustrations.  Second  Edition.  Cloth,  2.50 

Parvin's  Winckel's  Diseases  of  "Women.  Second  Edition. 
Including  a  Section  on  Diseases  of  the  Bladder  and  Urethra. 
150  Illus.  Revised.  Seepages.  Cloth,  3.00;  Leather,  3. 50 

Morris.    Compend  of  Gynaecology.    Illustrated.      Cloth,  i.oo 

Winckel's  Obstetrics.  A  Text-book  on  Midwifery,  includ- 
ing the  Diseases  of  Childbed.  By  Dr.  F.  Winckel,  Professor 
of  Gynsecology,  and  Director  of  the  Royal  University  Clinic  for 
Women,  in  Munich.  Authorized  Translation,  by  J.  Clifton 
Edgar,  M.D..  Lecturer  on  Obstetrics,  University  Medical  Col- 
lege, New  York,  with  nearly  200  handsome  Illustrations,  the 
majority  of  which  are  original.  8vo.  Cloth,  6.00;  Leather,  7.00 
JBf-  See  pages  2  to  5 for  list  of  New  Manuals. 


STUDENTS'  TEXT-BOOKS  AND  MANUALS.         11 


Obstetrics  and  Gynaecology: — Continued. 

Landis'  Compend  of  Obstetrics.  Illustrated,  sth  Edition, 
Enlarged.  Cloth,  i.oo;  Interleaved  for  Notes,  1.25 

Qalabin's  Midwifery.  By  A.  Lewis  Galabin,  M.D.,  F.R.C.P. 
227  Illustrations.  Leather,  3.50 

PATHOLOGY,  HISTOLOGY,  ETC. 

Stirling.     Outlines  of  Practical  Histology.    A  Manual  for 

Students.  2d  Edition.  368  Illustrations.  i2mo.  Cloth,  3.00 
Wethered.  Medical  Microscopy.  By  Frank  J.  Wethered. 

M.D.,  M.R.C.P.  98  Illustrations.  Cloth,  2.50 

Bowlby.  Surgical  Pathology  and  Morbid  Anatomy,  for 

Students.  135  Illustrations.  i2mo.  Cloth,  2.00 

Gilliam's  Essentials  of  Pathology.  A  Handbook  for  Students. 

47  Illustrations.  lamo.  Cloth,  2.00 

Virchow's  Post-Mortem  Examinations.  3d  Ed.  Cloth,  i.oo 

PHYSICAL  DIAGNOSIS. 

Fenwick.  Student's  Guide  to  Physical  Diagnosis.  7th 
Edition.  117  Illustrations.  iamo.  Cloth,  2.25 

Tyson's  Student's  Handbook  of  Physical  Diagnosis.  Illus- 
trated. i2mo.  Cloth,  1.25 

PHYSIOLOGY. 

Yeo's  Physiology.  Sixth  Edition.  The  most  Popular  Stu- 
dents' Book.  By  Gerald  F.  Yeo,  M.D.,  F.R.C.S.,  Professor  of 
Physiology  in  King's  College,  London.  Small  Octavo.  254 
carefully  printed  Illustrations.  With  a  Full  Glossary  and  Index. 
Seepages,  Cloth,  3.00;  Leather,  3.50 

Brubaker's  Compend  of  Physiology.  Illustrated.  Sixth 
Edition.  Cloth,  i.oo;  Interleaved  for  Notes,  1.25 

Kirke's  Physiology.  New  i3th  Ed.  Thoroughly  Revised  and 
Enlarged.  502  Illustrations,  some  of  which  are  printed  in  colors. 
{Blakiston1  s  Authorized  Edition?)  Red  Cl. ,  4.00 ;  Leather,  5.00 

Landois'  Human  Physiology.  Including  Histology  and  Micro- 
scopical Anatomy,  and  with  special  reference  to  Practical  Medi- 
cine. Fourth  Edition.  Translated  and  Edited  by  Prof.  Stirling. 
845  Illustrations.  Cloth,  7.00 ;  Leather,  8.00 

"  With  this  Text-book  at  his  command,  no  student  could  fail  in 

his  examination." — Lancet 

Sanderson's  Physiological  Laboratory.  Being  Practical  Ex- 
ercises for  the  Student.  350  Illustrations.  8va.  Cloth,  5.00 

PRACTICE. 

Taylor.  Practice  of  Medicine.  A  Manual.  By  Frederick 
Taylor,  M.D.,  Physician  to,  and  Lecturer  on  Medicine  at,  Guy's 
Hospital,  London  ;  Physician  to  Evelina  Hospital  for  Sick  Chil- 
dren, and  Examiner  in  Materia  Medica  and  Pharmaceutical 
Chemistry,  University  of  London.  Cloth,  2.00;  Leather,  2.50 

4?y-  See  pages  14  and  IS  for  list  »f  f '  Quiz-Comptnds  t 


12       STUDENTS'  TEXT-BOOKS  AND  MANUALS. 

Practice  : —  Continued. 

Roberts'  Practice.  New  Revised  Edition.  A  Handbook 
of  the  Theory  and  Practice  of  Medicine.  By  Frederick  T. 
Roberts,  M.D.,  M.R.C.P.,  Professor  of  Clinical  Medicine  and 
Therapeutics  in  University  College  Hospital,  London.  Seventh 
Edition.  Octavo.  Cloth,  5.50  ;  Sheep,  6.50 

Hughes.  Compend  of  the  Practice  of  Medicine.  4th  Edi- 
tion. Two  parts,  each,  Cloth,  i.oo;  Interleaved  for  Notes,  1.25 
PART  x. — Continued,  Eruptive  and  Periodical  Fevers,  Diseases 

of  the  Stomach,  Intestines,  Peritoneum,  Biliary  Passages,  Liver, 

Kidneys,  etc.,  and  General  Diseases,  etc. 
PART   n. — Diseases  of   the   Respiratory    System,  Circulatory 

System,  and  Nervous  System;  Diseases  of  the  Blood,  etc. 
Physicians'  Edition.    Fourth  Edition.    Including  a  Section 
on  Skin  Diseases.  With  Index,    i  vol.  Full  Morocco,  Gilt,  2.50 

From  John  A.  Robinson,  M.D.,  Assistant  to  Chair  of  Clinical 
Medicine,  now  Lecturer  on  Materia  Medica,  Rush  Medical  Col- 
lege, Chicago. 
"  Meets  with  my  hearty  approbation  as  a  substitute  for  the 

ordinary  note  books  almost  universally  used  by  medical  students. 

It  is  concise,  accurate,  well  arranged,  and  lucid,    .     .     .    just  the 

thing  for  students  to  use  while  studying  physical  diagnosis  and  the 

more  practical  departments  of  medicine. 

PRESCRIPTION   BOOKS. 

Wythe's  Dose  and  Symptom  Book.  Containing  the  Doses 
and  Uses  of  all  the  principal  Articles  of  the  Materia  Medica,  etc. 
Seventeenth  Edition.  Completely  Revised  and  Rewritten.  Just 
Ready.  32010.  Cloth,  i.oo;  Pocket-book  style,  1.25 

Pereira's  Physician's  Prescription  Book.  Containing  Lists 
of  Terms,  Phrases,  Contractions,  and  Abbreviations  used  in 
Prescriptions,  Explanatory  Notes,  Grammatical  Construction  oi 
Prescriptions,  etc.,  etc.  By  Professor  Jonathan  Pereira,  M.D. 
Sixteenth  Edition.  32mo.  Cloth,  i.oo  ;  Pocket-book  style,  1.25 

PHARMACY. 

Stewart's  Compend  of  Pharmacy.  Based  upon  Remington's 
Text-book  of  Pharmacy.  Third  Edition,  Revised.  With  new 
Tables,  Index,  Etc.  Cloth,  i.oo;  Interleaved  for  Notes,  1.25 

Robinson.  Latin  Grammar  of  Pharmacy  and  Medicine. 
By  H.  D.  Robinson,  PH.D.,  Professor  of  Latin  Language  and 
Literature,  University  of  Kansas,  Lawrence.  With  an  Intro- 
duction by  L.  E.  Sayre,  PH.G.,  Professor  of  Pharmacy  in,  and 
Dean  of,  the  Dept.  of  Pharmacy,  University  of  Kansas,  tamo. 
Second  Edition.  Cloth.z.oo 

SKIN  DISEASES. 

Crocker.  Diseases  of  the  Skin,  their  Description,  Pathology, 
Diagnosis,  and  Treatment,  with  Special  Reference  to  the  Skin 
Jhruptions  of  Children.  By  H.  Radcliffe  Crocker,  F.R.C  p.,  Phy- 
sician for  Diseases  of  the  Skin  in  I  niversity  College  Hospital. 
Second  Edition.  Revised  and  Enlarged,  with  92  Wood-cuts. 

Cloth,  5.00 

Van  Harlingen  on  Skin  Diseases.  A  Handbook  of  the  Dis- 
eases of  the  Skin.  By  Arthur  Van  Harlingen,  M.D.  $d  Edition. 
Enlarged  and  Illustrated.  i2mo.  In  Press. 

*S~  See  pages  a  to  5  for  list  of  New  Manuals. 


STUDENTS'  TEXT-BOOKS  AND  MANUALS.        13 

SURGERY   AND   BANDAGING. 

MoulUn's  Surgery,  by  Hamilton.  600  Illustrations  (some 
colored),  200  of  which  are  original.  Second  Edition. 

Cloth,  net,  7.00;  Leather,  net,  8.00;  Half  Russia,  net,  9.00 
***  Complete  circulars,  with  sample  pages  and  Illustrations,  free 
upon  application. 

Jacobson.  Operations  in  Surgery.  A  Systematic  Handbook 
for  Physicians,  Students,  and  Hospital  Surgeons.  By  W.  H.  A. 
Jacobson,  B  A.  Oxon.,  F.R.C.S.  Eng. ;  Ass't  Surgeon  Guy's  Hos- 
pital ;  Surgeon  at  Royal  Hospital  for  Children  and  Women,  etc. 
199  Illustrations.  1006  pages.  8vo.  Cloth.  5.00;  Leather,  6.00 
Heath's  Minor  Surgery,  and  Bandaging.  Tenth  Edition.  142 
Illustrations.  60  Formulae  and  Diet  Lists.  In  Press. 

Horwitz's    Compend    of    Surgery,    Minor    Surgery    and 
Bandaging,    Amputations,    Fractures,    Dislocations.   Surgical 
Diseases,  and  the  Latest  Antiseptic  Rules,  etc.,  with  Differential 
Diagnosis  and  Treatment.     By  ORVILLB  HOKWITZ,  B.S.,  M.D., 
Demonstrator  of  Surgery,  Jefferson  Medical  College,  sth  Edition. 
Enlarged  and  Rearranged.    Many  new  Illustrations  and  Formulae. 
i2mo.         Cloth,  i.oo ;  Interleaved  for  the  addition  of  Notes,  1.25 
*#*  The  new  Section  on  Bandaging  and  Surgical  Dressings  con- 
sists  of  32  Pages  and   41    Illustrations.     Every  Bandage  of  any 
importance   is  figured.      This,  with    the  Section   on  Ligation  ot 
Arteries,  forms  an  ample  Text-book  for  the  Surgical  Laboratory. 
Walsham.    Manual  of  Practical  Surgery.    Third  Edition. 
Bv  WM.  T.  WALSHAM,  M.D.,  F.R.C.S.,  Asst.  Surg.  to,  and  Dem- 
of  Practical  Surg.  in,  St.  Bartholomew's  Hospital;  Surgeon  to 
Metropolitan   Free  Hospital,  London.      With  318    Engravings. 
Set  page  2.  Cloth,  3.00 ;  Leather,  3.50 

URINE,  URINARY   ORGANS,  ETC. 

Holland.  The  Urine,  and  Common  Poisons  and  The 
Milk.  Chemical  and  Microscopical,  for  Laboratory  Use.  Illus- 
trated. Fourth  Edition.  i2mo.  Interleaved.  Cloth,  i.oo 

Ralfe.  Kidney  Diseases  and  Urinary  Derangements.  42  Illus- 
trations. i2mo.  572  pages.  Cloth,  2.75 

Marshall  and  Smith.  On  the  Urine.  The  Chemical  Analysis  ot 
the  Urine.  Colored  Plates.  12010.  Cloth,  i.oo 

Memminger.    Diagnosis  by  the  Urine.    Illus.      Cloth,  i.oo 

Tyson.  On  the  Urine.  A  Practical  Guide  to  the  Examination 
of  Urine.  With  Colored  Plates  and  Wood  Engravings.  Eighth 
Edition,  Enlarged.  i2mo.  Cloth,  1.50 

Van  Niiys,  Urine  Analysis.    Illus.  Cloth,  2.00 

VENEREAL  DISEASES. 

Hill  and  Cooper.  Student's  Manual  of  Venereal  Diseases, 
with  Formulae.  Fourth  Edition.  121110.  Cloth,  i.oo 

*S~  See  pages  14  and  15  for  list  of  f  Quiz-Compcnds  f 


PQUIZ-COMPENDS? 

The  Best  Compends  for  Students'  Use 
in  the  Quiz  Class,  and  when  Pre- 
paring for  Examinations. 

Compiled  in  accordance  -with  the  latest  teachings  of  promi- 
nent Lecturers  and  the  most  popular  Text-books. 

They  form  a  most  complete,  practical,  and  exhaustive 
set  of  manuals,  containing  information  nowhere  else  col- 
lected in  such  a  condensed,  practical  shape.  Thoroughly 
up  to  the  times  in  every  respect,  containing  many  new 
prescriptions  and  formulae,  and  over  two  hundred  and 
fifty  illustrations,  many  of  which  have  been  drawn  and 
engraved  specially  for  this  series.  The  authors  have  had 
large  experience  as  quiz-masters  and  attaches  of  colleges, 
with  exceptional  opportunities  for  noting  the  most  recent 
advances  and  methods. 

Cloth,  each  $1.00.  Interleaved  for  Notes,  $1.25. 
No.  i.  HUMAN  ANATOMY,  "  Based  upon  Gray."  Fifth 
Enlarged  Edition,  including  Visceral  Anatomy,  formerly 
published  separately.  16  Lithograph  Plates,  New 
Tables,  and  117  other  Illustrations.  By  SAMUEL  O.  L. 
POTTER,  M.A.,  M.D.,  M.R.C.P.  (Lond.),  late  A.  A.  Surgeon  U.  S. 
Army,  Professor  of  Practice,  Cooper  Medical  College,  San  Fran- 
cisco. 

Nos.  2  and  3.     PRACTICE  OF  MEDICINE.    Fourth  Edi- 
tion.    By  DANIEL  E.  HUGHES,  M.D.,  Demonstrator  of  Clinical 
Medicine  in  Jefferson  Medical  College,  Philadelphia.  In  two  parts. 
PART  I. — Continued,  Eruptive,  and  Periodical  Fevers,  Diseases 
of  the  Stomach,  Intestines,  Peritoneum,  Biliary  Passages,  Liver, 
Kidneys,  etc.  (including  Tests  for  Urine),  General  Diseases,  etc. 

PART  II. — Diseases  of  the  Respiratory  System  (including  Phy- 
sical Diagnosis),  Circulatory  System,  and  Nervous  System;  Dis- 
eases of  the  Blood,  etc. 

***  These  little  books  can  be  regarded  as  a  full  set  of  notes  upon 
the  Practice  of  Medicine,  containing  the  Synonyms,  Definitions, 
Causes,  Symptoms,  Prognosis,  Diagnosis,  Treatment,  etc.,  of  each 
disease,  and  including  a  number  of  prescriptions  hitherto  unpub- 
lished. 

No.  4.  PHYSIOLOGY,  including  Embryology.  Sixth 
Edition.  By  ALBERT  P.  BRUBAKER,  M.D.,  Prof,  of  Physiology, 
Penn'a  College  of  Dental  Surgery ;  Demonstrator  of  Physiology 
in  Jefferson  Medical  College,  Philadelphia.  Revised,  Enlarged, 
with  new  Illustrations. 

No.  5.  OBSTETRICS.  Illustrated.  Fifth  Edition.  By 
HENRY  G.  LANDIS,  M.D.  Edited  by  WILLIAM  H.  WELLS,  M.D., 
Assistant  Demonstrator  of  Clinical  Obstetrics,  Jefferson  College, 
Philadelphia.  New  Illustrations. 


BLAKISTON'S  ?  QUIZ-COMPENDS  ? 

No.  6.  MATERIA  MEDICA,  THERAPEUTICS,  AND 
PRESCRIPTION  WRITING.  Fifth  Revised  Edition. 

With  especial  Reference  to  the  Physiological  Action  of  Drugs, 
and  a  complete  article  on  Prescription  Writing.  Based  on  the 
Last  Revision  of  the  U.  S.  Pharmacopoeia,  and  including  many 
unofficinal  remedies.  By  SAMUEL  O.  L.  POTTER,  M.A.,  M.D., 
M.R.C.P.  (Lond.),  late  A.  A.  Surg.  U.  S.  Army ;  Prof,  of  Practice, 
Cooper  Medical  College,  San  Francisco.  Improved  and  Enlarged, 
with  Index. 

No.  7.  GYN^COLOGY.  A  Compend  of  Diseases  of  Women. 
By  HENRY  MORRIS,  M.D.,  Demonstrator  of  Obstetrics,  Jefferson 
Medical  College,  Philadelphia.  45  Illustrations. 

No.  8.  DISEASES  OF  THE  EYE  AND  REFRACTION, 
including  Treatment  and  Surgery.  By  L.  WEBSTER  Fox,  M.D., 
Chief  Clinical  Assistant  Ophthalmological  Dept.,  Jefferson  Med- 
ical College,  etc.,  and  GEO.  M.  GOULD,  M.D.  71  Illustrations,  39 
Formulae.  Second  Enlarged  and  improved  Edition.  Index. 

No.  9.  SURGERY,  Minor  Surgery  and  Bandaging.  Illus- 
trated. Fifth  Edition.  Including  Fractures,  Wounds, 
Dislocations,  Sprains,  Amputations,  and  other  operations;  Inflam- 
mation, Suppuration,  Ulcers,  Syphilis,  Tumors,  Shock,  etc. 
Diseases  of  the  Spine,  Ear,  Bladder,  Testicles,  Anus,  and 
other  Surgical  Diseases.  By  ORVILLE  HORWITZ,  A.M.,  M.D., 
Demonstrator  of  Surgery,  Jefferson  Medical  College.  Revised 
and  Enlarged.  98  Formulae  and  167  Illustrations. 

No.  10.  CHEMISTRY.  Inorganic  and  Organic.  For  Medical 
and  Dental  Students.  Including  Urinary  Analysis  and  Medical 
Chemistry.  By  HENRY  LEFFMANN,  M.D.,  Prof,  of  Chemistry  in 
Penn'a  College  of  Dental  Surgery,  Phila.  Third  Edition,  Revised 
and  Rewritten,  with  Index. 

No.  ix.  PHARMACY.  Based  upon  "  Remington's  Text-book 
of  Pharmacy."  By  F.  E.  STEWART,  M.D.,  PH.G.,  Quiz-Master 
at  Philadelphia  College  of  Pharmacy.  Third  Edition,  Revised. 

No.  12.  VETERINARY  ANATOMY  AND  PHYSIOL- 
OGY. 29  Illustrations.  By  WM.  R.  BALLOU,  M.D.,  Prof,  of 
Equine  Anatomy  at  N  Y.  College  of  Veterinary  Surgeons. 

No.  13.  DENTAL  PATHOLOGY  AND  DENTAL  MEDI- 
CINE. Containing  all  the  most  noteworthy  points  of  interest 
to  the  Dental  student.  Second  Edition.  By  GEO.  W.  WARREN, 
D.D.S.,  Clinical  Chief,  Penn'a  College  of  Dental  Surgery,  Phila- 
delphia. Second  Edition,  Enlarged  and  Illustrated. 

No.  14.  DISEASES  OF  CHILDREN.  By  DR.  MARCUS  P. 
HATFIELD,  Prof,  of  Diseases  of  Children,  Chicago  Medical 
College.  Colored  Plate. 

Bound  in  Cloth,  $1.    Interleaved,  for  the  Addition  of  Notes,  $1.25. 

4^"  These  books  are  constantly  revised  to  keep  up  with 
the  latest  teachings  and  discoveries,  so  that  they  contain 
all  the  new  methods  and  principles.  No  series  of  books 
are  so  complete  in  detail,  concise  in  language,  or  so  well 
printed  and  bound.  Each  one  forms  a  complete  set  of 
notes  upon  the  subject  under  consideration. 

Illustrated  Descriptive  Circular  Free. 


GOULD'S  NEW 

MEDICAL  DICTIONARY. 

Based  on  Recent  Medical  Literature. 


Small  8vo,  Half  Morocco,  as  above,  with  Thumb  Index,  .   .  $4.25 
Plain  Dark  Leather,  without  Thumb  Index, 3.25 


A  compact,  concise  Vocabulary,  including  all 
the  Words  and  Phrases  used  in  medicine,  with 
their  proper  Pronunciation  and  Definitions. 


"  One  pleasing  feature  of  the  book  is  that  the  reader  can  almost 
invariably  find  the  definition  under  the  word  he  looks  for,  without 
being  referred  from  one  place  to  another,  as  is  too  commonly  the 
case  in  medical  dictionaries.  The  tables  of  the  bacilli,  inicrococci, 
leucomai'nes  and  ptomaines  are  excellent,  and  contain  a  large 
amount  of  information  in  a  limited  space.  The  anatomical  tables 
are  also  concise  and  clear.  .  .  .  We  should  unhesitatingly 
recommend  this  dictionary  to  our  readers,  feeling  sure  that  it  will 
prove  of  much  value  to  them." — American  Journal  of  Medical 
Science. 

JUST  PUBLISHED. 

GOULD'S    POCKET    DICTIONARY.     12,000 
Medical  Words  Pronounced  and  Defined. 
Leather,  gilt  edges,  $1.00;  with  Thumb  Index,'$l.25 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 


THIS  BOOK  IS  DUE  ON  THE  LAST  DATE 
STAMPED  BELOW 


)Ml  18  W> 

OCT  I*  t«6 

i  FEB  281918 

OCT.  18 1920 

15May'53WL 
JUN  61953  LU 


YB  16419 


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